Optimizing track mode for snow driving

Hello everyone,

I've just returned from Winter Driving School, now that my MYP has track mode. I thought I would share the settings I came up to optimize track mode for high performance driving on snow (high performance here refers fine control, not outright speed).

Here's a video - see below for discussion of settings & analysis.

Before my MYP, I had Audi's and Subaru's that would let me turn off the stability program. That was much more effective in snow than an MY without track mode. I had hoped they'd eventually give us track mode, and that with it, my MY would be able to get into the same ball park for car control as my prior cars. I am happy to report that that is exactly what happened - but it was not a direct, or short path to that goal. If you just want to know the numbers I'll give the spoilers now. Read on if you're interested in why these ended up being the right numbers or in how we got to them.

Notes:

• These settings were with around 200 lbs of cargo in the trunk
• The track had a solid foundation of ice with several inches of snow that we wore through in several spots.
• These bias and regen settings are likely not optimal for either all-ice or all-snow, but they'd be fine as a starting point
• The stability setting is critical, and would be the same for any conditions

Settings:
Front/rear power bias: 30/70% (anywhere between 35/65 and 20/80 was acceptable)
Stability: -9
Regen: 75% on the skidpad, 30-40% on the slalom

IMPORTANT: Watch out for ABS on ice - with regenerative braking on even partially, if you trigger ABS, the car will keep doing ABS after you take your foot off the brake, b/c it still does ABS for regen-braking. That means you can't threshold-brake to get back your grip. Or at least to do it w/ regen on, you would have to actually press the accelerator to the point where the car wasn't braking anymore, reverse-modulate by lifting to brake more, and pressing to brake less. Crazy-making, that was too next-level single-pedal driving for my brain, I didn't try.

Ok, I'll jump directly to the biggest spoiler from all that: the -9 stability setting. It took a lot to get to this.

-10 does not work well because the MY has open differentials, and uses the brakes to force power from a slipping wheel to the other side of the differential (some call this EDL - Electronic Differential Locking). However, Tesla considers this part of "stability," and when stability is at -10, it's completely off. -9 is the magic number because it enables just enough EDL to reliably get wheels on both sides of an axel to spin together, without cutting out power or doing other tricks to stop you from sliding intentionally.

Here's how we came to all the above...

On the first day, my results were really frustrating - about 1/3 of the time, I could initiate controlled oversteer readily, and keep it controlled for 3-8 seconds. 1/3 of the time it wouldn't come easily, I'd have to slam the accelerator to get oversteer, and then it would be wild/uncontrollable. And 1/3 of the time the car just wouldn't do anything except just keep going slowly in whatever direction I was pointing it, with no understeer or oversteer, no matter how hard I pressed the accelerator.

I tried many combinations of settings that day, ranging from 50/50 to 20/80 bias, 30-80% regen, and -10, -7, and -6 stability. The other tweaks only had a minor impact on how often or how long I could maintain controlled oversteer, or how likely I was to wildly oversteer & spin out. There was no happy medium - always a split between too much, not enough, and always unpredictable.

We had a social event that evening, and I had a great super technical conversation and super constructive conversation with one of the instructors. We had several theories:

1. Maybe even with stability as low as I can put it, the car is still doing some stability control
2. Maybe there is a timer, and it's only willing to let me spin wheels wildly for a limited time
3. Maybe part of the problem is that when the details are just right, and open differential can still spin both wheels (like if they have exactly the same amount of grip and are going the same speed when you overpower them)
4. Maybe the built-in "Drift Mode" setting - which you can not edit, but you can see what settings it is using - has a hidden change that it does that is not available to me in the custom settings

So, we came up with the following experiments to answer the above questions, and he let me go out to the track early on day 2 to conduct them:

1. Get on some ice, point the car straight, and floor it for a long time. See if it eventually cuts power
   1. It did not
2. Same as above, but have observers on both side of the car - see if all four wheels are spinning at the same time
   1. They were not. Sometimes wheels on both sides of an axel would spin, other times it would go back & forth between one side and the other.
3. Turn on Drift mode, and see if I was maintain a continuous drift without it ending except by my choice
   1. I was
4. Duplicate Drift mode's settings in a custom setting group, and see if I was still able to maintain continuous drift (thus proving or disproving whether the built-in Drift mode has a special hidden setting)
   1. I was, and thus, it does not.

Armed with all of the above information, the instructors all concluded that the car still has some kind of traction or stability control going on, even when it's set to -10. I was not convinced. The one thing we didn't have an experiment for was to determine whether the inconsistent results were simply because an open differential has inconsistent behavior.

That is when I thought of trying -9. It was more of a hail-mary, I never believed it was going to work. My thinking was this:

• If an open diff sometimes will still spin both wheels, then maybe all the times I was able to cause oversteer, it is because in those cases, by chance, I got both wheels to spin.
• I had a feeling that the alternating spinning and stopping of wheels that they reported during the straight-line acceleration test was because as I moved forward (slowly b/c of all the slipping), a wheel that was once on ice would eventually find snow, and if the opposite wheel was then on ice, I'd expect the slipping to switch from one wheel to the other
• Maybe, with a lot of luck, if I add the smallest amount of stability programming that I can add, it will bring in just enough EDL to force both wheels to spin whenever one is spinning, but not so much as to prevent me from getting the car to slide.

Well it worked! We did one more test:

• Straight-line floored acceleration with observers on both sides, and front/rear bias at 50/50
  • All four wheels spun continuously until I took my foot off the accelerator!

After that, I tried 25/75 front/rear bias and hit the skid pad again. For the first time, I was able to "drift" in all-wheel-drive mode for as long as I wanted, and it worked every single time. We never did bother to figure out why Drift Mode also enabled this, even though it uses a Stability setting of -10. I think it is a combination of me already being moving and turning before flooring it, and turning off the front motor means the equation for keeping wheels on both sides of the read differential became much simpler.

 

[gx9901]

@avramd As I'm getting ready for the winter driving school this weekend, I've got a question for you regarding your experience with the car's range. What was your starting SOC, ending SOC, and how much track time did you guys get for the day?

I just got a copy of the schedule and it looks like we'll get six 25-minute sessions on the track with an instructor during the day. I've been to this track during the summer for HPDE and I always arrive with SOC at around 93%. For HPDE I can do about 4.5 out of 7 the 20-minute sessions we are allotted before I have to quit with about 13~15% SOC or risk not making it home. I imagine winter driving school won't drain the battery like HPDE so hopefully no issues lasting the entire day. But it will be a lot colder so I'm thinking starting SOC might be in the 85% range. Anyway, just trying to get an idea on what to expect. Thanks!

Answering my own question here for future reference. I charged to 100% overnight and arrived at the track (about 25 minutes away) at 91%. Turns out this is much less taxing on the battery than the summer HPDE sessions so I got through all six 25 minute sessions with over 50% of battery left.

Winter driving school was a lot of fun and I learned new things about the car and hopefully am a better driver for it. Finished the day with several oversteer spinouts and almost got stuck in deep snowbank twice, where I found that "Slip Start" really works. I feel like I improved with car control throughout the day so I'm really happy with how it went.

I think anyone who has access to some sort of winter driving school should really give it a try, although I think for us Tesla drivers, it would probably be best if you have a car with Track Mode. I tried my first lap in Sport mode and stability control severely cutoff power when I slid on a turn, so without the ability to dial stability control way down would have made for a long day, I think. It was funny to see a couple of instructors digging deep into instruction manuals of a Subaru and a Toyota trying to figure out how to turn off traction/stability control and referring to them as designed by lawyers.

 

[avramd]

@avramd As I'm getting ready for the winter driving school this weekend, I've got a question for you regarding your experience with the car's range. What was your starting SOC, ending SOC, and how much track time did you guys get for the day?

Interesting question! TeslaFi to the rescue...

I can't say for sure how many sessions we had, I'm not sure how many times I put the car in park during a session. There are 11 "drives," but it's probably 6-8 sessions.

77% SOC at start of track time; day 1 of the class put 19 miles on the odometer; finished with 44% SOC.

Here is day 1:

Here are the stats for just the track time:

 

[avramd]

Answering my own question here for future reference. I charged to 100% overnight and arrived at the track (about 25 minutes away) at 91%. Turns out this is much less taxing on the battery than the summer HPDE sessions so I got through all six 25 minute sessions with over 50% of battery left.

Shoot, so sorry that I didn't see this until just now.

Finished the day with several oversteer spinouts and almost got stuck in deep snowbank twice, where I found that "Slip Start" really works.

Please describe what that was like. I've never found Slip Start to be useful. My experience of it is that it cuts out power almost immediately after it senses wheel spin - much faster than regular mode. Then I just sit there with my foot on the pedal in silence with no activity of any kind, until I take my foot off. Then I try it again, and it's the same. I wonder if something is actually wrong with my car, w/rt Slip Start mode.

I feel like I improved with car control throughout the day so I'm really happy with how it went.

What did you end up settling on for settings? What others did you try & what difference did you find with them?

What were you running for tires & what were the conditions like? Did they have a good base of ice under the snow, or did you guys get through the snow ever to the real surface (dirt, gravel or pavement?)

 

[gx9901]

Interesting question! TeslaFi to the rescue...

I can't say for sure how many sessions we had, I'm not sure how many times I put the car in park during a session. There are 11 "drives," but it's probably 6-8 sessions.

77% SOC at start of track time; day 1 of the class put 19 miles on the odometer; finished with 44% SOC.

Here is day 1:

View attachment 911631

Here are the stats for just the track time:

View attachment 911637

That's cool. I think perhaps the nature of the driving schools are different between yours and mine. I think I drove close to 50 miles during the WDS. We basically drove around the track all day during the six sessions. A lot of what they talked about are principles that are used during dry conditions, but with the slippery conditions we could experience handling limits and car control at low speeds.

Shoot, so sorry that I didn't see this until just now.

No problem at all! I just wanted to see if I could get some idea on consumption but it turned out to be a non-issue.

Please describe what that was like. I've never found Slip Start to be useful. My experience of it is that it cuts out power almost immediately after it senses wheel spin - much faster than regular mode. Then I just sit there with my foot on the pedal in silence with no activity of any kind, until I take my foot off. Then I try it again, and it's the same. I wonder if something is actually wrong with my car, w/rt Slip Start mode.

For the first one I spun and went head first into a large pile of snow. Probably at least 4~5 feet tall. It seemed to be stuck pretty good and the car wouldn't move when I tried reversing. I tried Off Road Assist next and it wouldn't really move either. Slip Start got the car moving slightly so I just rocked it back and forth between D & R while flooring it until the car was able to back out of the pile of snow.

For the second one I spun during a slippery turn and landed parallel to the track into the snow bank on the left. The instructor thought we might need to call a truck to pull us out since there were a lot of snow beneath the car. I tried Slip Start again and after flooring it back and forth it seemed to catch some pavement and eventually I was able to rock the car out of the snow bank. It probably helped that many sections of the track had snow melted to the point where pavement was showing, although the area where I spun out was pretty much all snow/ice since I don't think too much sun got to that area.

To me when Slip Start is activated, it does feel like the wheels are spinning with some power (not sure if full power) to get the car to power out of the snow situation. It definitely didn't cut power. I felt almost complete power cut while slipping during a lap using Sport mode, and Slip Start did not do that.

What did you end up settling on for settings? What others did you try & what difference did you find with them?

I used your setting most of the time. I didn't really change it until it was a bit too late (afternoon, I tried 50/50), when a lot of the snow melted off so a lot of the track had some pavement showing and I couldn't really tell much difference since we had lot more traction by then.

What were you running for tires & what were the conditions like? Did they have a good base of ice under the snow, or did you guys get through the snow ever to the real surface (dirt, gravel or pavement?)

I have Michelin X-Ice Snows. I have no idea how they performed since I have nothing else to compare them to. It felt like they lacked grip while I was spinning out doing turns at some slippery spots though. LOL! I think most cars there spun into snow bank at some point, but I feel like I might have spun out the most.

We started the day in around 10F temperature and the track was covered in snow. I don't think there's much Ice underneath since before we got 1.5 feet of snow last week, the snow accumulated previously was melting at a pretty good pace and most roads were totally clear and dry. The morning sessions were pretty much all on snow covered track, and it got progressively more slippery as people drove on it and temperature started increasing. It warmed up to mid 20's with bright sun out by early afternoon and by then many sections of the track had some pavement showing. At that point the instructor had me looking for traction, similar to driving a "rain line", as I drove around the track. There were a couple of really slippery spots that remained toward the end but a lot of it almost felt like when I went there in the summer. They had a skidpad, but there was a huge patch of ice in one of the sections around the circle and when I hit that the car just slid straight ahead, so I was not able to try to drift around it.

As I said, it was a great experience and I'm glad to have seen this thread so I could go seek out a WDS to attend.

 

[avramd]

I got a chance to do a little more experimenting in a recent snowfall, in a vacant abandoned parking lot.

• Real-time handling-balance adjustment
• Real-time regen-braking level adjustment
• Mid-slide forward/reverse shifting
• Increased accelerator pedal resistance/rebound

Real-Time Handling Balance Adjustment​

This worked very well. I would throw the car into a tail slide - more than you would ever want in a real situation, to emulate an accidentally over-aggressive tail slide. I kept my right hand resting on top of the display with my thumb either on the handling-balance slider at 65%, or hovering over it. Once I had excess tail slide, I would slide my thumb down to 25% or 0%. This had an immediate - but not jarring - effect of starting to reduce the car's rotation, and then reverse it. Once the car was back at an appropriate degree of tail slide, I would slide my thumb back to my approximate default balance setting.

The granularity that is available is excessive for a real-time application. You can choose to feather it back to your original setting instead of jumping back to it, and you get to decide when to go back. It would be enough just to have a 2nd setting "alternate balance," and a button that when pressed uses the other setting. While feathering it back is nice, I found that if I simply returned to my default when the car's rotation was close to zero, there was no benefit from feathering, and there is a big benefit to paying as little attention to that control as possible, and focusing on the road, steering and pedals.

I told a friend about this, and he pointed out that we have dials built into the steering wheel. It would be really slick if we could adjust the power balance from the steering wheel.

My test application was purely for problem solving - fixing excessive rotation. However this would probably also be very effective in preventing unwanted rotation. At various moments during a slalom, there will be times where you'd like to apply more power, but you know that it'll cause the car to rotate more than you want. Tweaking the balance for the immediate circumstances could enable you to ensure you don't over-rotate, and getting it exactly right could enable you to maximize how much power you can apply while keeping the car's attitude towards the next turn exactly how you want it. Normally the attitude you want determines how much power you can apply, and you have to apply it just right to get the desired attitude. This could enable a very skilled driver to always deliver the maximum amount of power that the current traction can support, and independently choose the car's attitude towards the next turn. Personally I'm nowhere near good enough to start messing with that; now that I know it works, my best play is to endeavor to not need it in the first place, and only use it to minimize how far off I get when I make a mistake.

Real-Time Regen-Braking Adjustment​

This does not work. When I change the regen level while driving, the effect is not immediate. I did not figure out what has to happen before it takes effect. It always eventually did, and it did not require a gear shift or stopping. At a minimum it seemed to require some amount of time to pass during which no regen-braking is happening. There may be some other fact that has to switch from false to true that I didn't think of or sense, or it might just be a timer.

This isn't a big deal, I think the real play here is simply to practice "reverse threshold-braking;" Train our brains to act as though there is another brake pedal above the accelerator, and our right is wedged between them. Lifting my foot up on the accelerator is "pressing" this imaginary brake pedal upwards, and that is activating the brakes. To deactivate ABS in the moment, you just need to brake less, until the wheels stop locking.

The hardest part of it is that we think of pressing the accelerator as adding power, and that that will make an emergency braking situation worse. However, the reality of it is that if the engine is slowing you down, then adding a little bit of power really is going to do exactly what we want - slow us down less. It should just be a simple case of unlearning a simple habit and relearning a more sophisticated version of it.

I'm starting to get there. When driving in snow, I am proactively thinking "As I approach this stop sign, ease the accelerator gently - and look for the ABS kick in; if it does, push the pedal back down just a little, to just where it was before the ABS kicked in." It's not muscle memory yet, but as long as I'm thinking it through in advance, it works.

Note that the all of this is 100% applicable to all Teslas; you don't have to have Track Mode to apply this technique - we all need to learn it. We do all have a "low" regen setting - but even that only helps if you thought of switching to it. The best thing we can do is learn to reverse threshold-brake with full regen b/c if you're in an emergency, you don't have time to change the setting.

Mid-slide Forward/Reverse Shifting​

This worked ok. It's gimmicky and unreliable. It won't shift above a certain road speed of course. The trick is that if you are in the middle of spinning out (doing a 180º spin, whether intentional or not), there is a moment in there that the car is sliding entirely sideways, and its forward momentum is zero. The actual speed can be anything, and you will still be allowed to shift, b/c the car doesn't care about its inertia, it only cares about its wheel speed.

I did manage a couple of deliberate spin-outs in which I successfully switched to reverse mid-spin, and was able to continue applying power in the direction of the car's existing inertia, but with the car facing the opposite direction. There are some track situations in which this could be more effective than what people do today:

The "Scandinavian flick" is when you time the recovery from one fishtail coming off of one turn such that your tail swings directly into a fishtail in the opposite direction that is coordinated with the geometry of the next turn. Hard to explain, but I think I managed one in the video at the top of this thread. This is more effective than just a normal turn b/c it gets all four wheels pointed sooner in the new direction that you will want to accelerate, so you can apply power sooner. However, with mid-slide reverse, when the next turn is a hairpin, there is another option:

You can come off of the last turn - a sweeping right in the video above, and instead of recovering from the left fishtail into a new right fishtail, you could extend the left fish-tail into a 180º, continue in reverse until you are past the hairpin, and then shift into forward and accelerate. This means that you're only doing a 90º rotation of the car between the last fishtail and the forward acceleration. The Scandinavian Flick is a 270º rotation of the car - it is spending a lot more time with the car pointed in a different direction than the direction you want to apply power in.

I may play with this at this weekend's WDS. It might be deemed unsafe b/c it's unexpected direction of momentum. It might break the system they have for designing the tracks so that two cars on the track at the same time are never in danger of hitting each other.

Increased Accelerator Resistance/Rebound​

One big challenge I had at the first WDS was the accelerator pedal being too light. Often I needed to apply more power, but to a very small degree, and my foot action was not precise enough, I would repeatedly get more power than I wanted.

I went to Home Depot and bought a two-pack of contractor sponges. I jammed one of them under the accelerator pedal arm. It was a perfect fit. I've had it in there for a week, and it hasn't budged. I haven't had a chance to try this in real slip conditions, but it is providing a small but noticeable additional resistance to the pedal. I'm optimistic

 

[avramd]

As I said, it was a great experience and I'm glad to have seen this thread so I could go seek out a WDS to attend.

I'm really glad to hear that.

I was hesitant to start this thread b/c I knew I had a lot to say, and that I had barely posted here before; I was concerned people weren't going to appreciate a long post from a stranger, or that there might be a whole lot of negative responses of some kind. I'm really glad it has turned into a positive thread, and the fact that somebody else actually went out and took significant action and got positive results is as good of an outcome as one can hope for from a thread!

 

[avramd]

Hey everyone! I thought I would chime in with a report from WDS II.

• Tire change - studded Hakka 9's -> studless Hakka R5's
• Accelerator Pedal resistance
• Real-time handling balance adjustment
• Updated setting
• Reverse Threshold Breaking
• Final Results

Tire Change​

First, I have to say that the jury is out on the Hakka RV's vs studded Hakka 9's. The R5's performed very well, but there were some extremely slick spots on the track where I was suddenly just a passenger - absolutely no input had any result whatsoever. It was like being in free-fall, just waiting until the car got to a spot that had more traction. I can not say for sure whether the same would have happened with the studded tires or not. There were certainly moments at WDS I where I felt that the studs were doing "almost nothing." I don't recall ever feeling they were doing literally nothing.

What makes this hard to assess is that most other cars at WDS II were behaving exactly the same as mine in those slick spots, and I don't recall that happening to many cars a month ago. I did not, unfortunately, think to survey which cars had studs this time, and pay attention to whether they were in the group that was experiencing "free-fall" like me or not.

As impressed as I was at how quiet the studded Hakkas were, that is relative to what people expect from studs. I do very much enjoy having the car now be silent with her snow shoes on. I believe I'm still within Nokian's 30 day satisfaction guarantee, and could have these replaced for free with brand new studded Hakka 10's, and I am not pulling that trigger.

Accelerator Pedal Resistance​

This simple sponge that I stuffed behind the accelerator pedal arm is working perfectly:



There were only a couple instances of me pushing the pedal harder than I meant to, and causing a loss of control that was supposed to get me either controlled acceleration or weight transfer to get the tail end to grip. There were a few times when I did lifting off the accelerator more than I wanted to - causing more regen braking, and thus triggering ABS when I was trying to avoid that. I tried stuffing the second sponge under there, but that was way too much resistance. Ultimately, I was able to fine-tune my foot control in both directions, with the end result being that I nearly always got the amount of regen braking that I intended to. It wasn't always the right amount for the situation, but they were legit bad calls on my part.

I am not recommending that anybody do this, but I am not discouraging it either. It is obviously risky to deliberately have an unattached object in the area of the pedals. My experience so far, and these are just my opinions, is that this sponge fits perfectly, and has just the right properties to function as desired. Namely, it is just snug enough to be unlikely to move; It has quite a bit of friction with the carpet - based on how much effort it takes to get it in there, I feel there is very little likelihood that it is ever going to move. The area it projects into is somewhere that nobody should ever put their foot anyway (under the break pedal), so that projection does not concern me. The amount of resistance it provides is well within the range of what is expecte for accelerator. I intend to leave it there permanently, and simply check it occasionally for wear. The only meaningful risk that I can think of is that if it disintegrates, then it could become dislodged - if part of it were to become loose in the pedal area, it could cause distraction. I don't think there is any way that it could prevent normally functioning of anything, but if it distracts a driver at a bad moment, it could cause a delayed reaction, or a driver to focus on something unimportant over something important.

Real-time Handling Balance Adjustment​

I ended up doing very little of this at WDS II. ICYMI, this was an experiment I tried in a snowy parking lot: Changing the handling balance in the moment when a situation would benefit from more power in front, but not - or less - at the back. There are a few reasons I didn't do it much. One was that I didn't want to debate it with the instructors. Another was that as my own skills improved, I was dialing back the amount of rear-bias I was using, and found myself less frequently in situations where the back end was too loose and there was a need for it.

Probably the biggest reason (which is itself affected by the reduced need), is that I found that keeping a hand on the display changed my focus as a driver. The change in body position changed my relationship with the car. I found myself putting more attention into this control, and less into everything else, than warranted. I was using the control when there was no real need for it, and my actual driving precision was noticeably less. I imagine that this is something I could improve on with practice, but I found that I didn't want to. I preferred to improve my actual driving rather than focus on what was possible from this trick.

I may come back to it in the future. For this weekend itself, I was getting more value out of the course ignoring this option than using it.

Updated Settings​

My exit settings once the course was over were:

• 55% rear, 45% front handling bias
• -9 stability assist
• 75% regen braking

I started the weekend using 65% rear bias instead of the larger numbers I've reported here previously. My theory was that the closer to 50/50 that I could get while still being able to get the car to do what I wanted, the more effective I would be. Part of the idea was that while swinging the tail wildly is super-fun, and good for building muscle memory around controlling the car, it is ultimately slower and more wasteful than smaller tail swings. The fastest cars on a track typically also seem to be amongst the least dramatic. By mid-day Saturday, I was using 60/40. Mid Sunday I switched to 55/45. With each adjustment, my slaloms got tighter and tighter.

This also coincided with the instructors' advice to start turning well before the next cone. They said that you should be nearly finished your turn before you're even at the cone, so you can focus 100% on accelerating past it, and because if you are not, you'll end up wide. That will make you late to the next cone, and it will compound over a series of cones until you miss one entirely. I found that they were right, and I also found that it only takes a tiny amount of tail slide to get the car pointed the right direction to pass the back side of the current cone and be set up for the optimum approach to the next one.

I'll comment on the high regen setting next

Reverse Threshold Breaking​

One of my biggest objectives was to re-train my brain to approach regenerative emergency braking as natural instead of counter-intuitive. There were two reasons for this: 1) My theory was that strong regenerative breaking is not inherently problematic, it is just different than what we are accustomed to, and 2) It will be very rare in the real world that I will put my car in track mode, so if I do find myself in an ABS situation, I want to have the muscle-memory to automatically optimize it based on how the car is likely to be set, not for how I could have set it after it is too late.

ICYMI, we all have a challenge when using full regen braking: If you end up on a very slippery surface, just lifting off of the accelerator can trigger your ABS, you don't need to touch the brake pedal. ABS is better than nothing, but not very good at stopping the car in the shortest possible distance. In a normal car, the best thing to do in an emergency stop - particularly on a slippery surface - is modulate the brake pedal, looking for "that perfect spot" where the ABS almost never triggers. When you trigger ABS just by lifting off of the accelerator, what you need to do to improve it is counterintuitive: Press the accelerator back down a little. You are still looking for "that perfect spot" where ABS almost never gets activated, but once it is you need more accelerator to make it stop. It is really the same - you tried to slow down to abruptly, you need to ask for less deceleration. But it is hard to get your brain to press the accelerator more when what you want is to stop faster.

Ultimately, it appears that all of this theory was spot-on. I was ultimately able to train my brain to reverse-threshhold-brake effectively using 75% regent. I was very happing with my emergency braking results all weekend long. The next step will be to practice emergency stopping with 100% regen in snow & ice conditions. One thing I did find is that as I approached zero mph (maybe around 5-8), regen braking was frequently not enough, and I needed to switch to the brake pedal. Track mode automatically puts the car in "roll stop" mode, no matter what it was in before. I'm unclear on whether this is simply the natural behavior of electric regen breaking, or if the software is dialing back the regen at low speeds.

Final Results​

I did do the time trials at the end of the course this time. I did very well relative to the other students. We go three runs each. My final results were middle-of-the-pack b/c you get penalties for certain mistakes that would be a cheat: hitting a cone, ignoring a cone, or failing to stop in the designated stopping area at the end. I was out of the box on one, and I missed a cone on one. But ignoring the penalties, two of my runs were the best of the day by 4 seconds each (1:24 vs 1:28). The next few best times were ~1 sec difference from each other.

My first run really doen't count as a best-in-class b/c the cone I skipped enabled me to go straight instead of turn. It was a mistake, but it gave me an advantage. I suspect it was less than a 4 second advantage, and it may have been the best time of the day if I'd read the course and driven it correctly, but we'll never know.

My last run was legitimately the best run of the day. The huge 30 second penalty does not reflect the advantage I got by stopping 2 feet outside of the box, it was legitimately 4 seconds better of a time than the next best time.

The two people who got the first & second best results of the day were legitimately better drivers than me. They were both in Subarus with old-school AWD; one a 2017 STI, the other an early 2000's WRX. Both of these have viscous-coupled center and rear differentials - the best AWD for snow that I know of for under 6 figures. The reason I got better times than them is that there were two small straight-aways with packed now but no ice that were very grippy. Molly's immediate and powerful acceleration on these straights was phenomenal, and enabled me to make up time where the better drivers were beating me on the turns. I suspect I may have been the 3rd or 4th most effective driver out of the 20 students, although the guy in the RWD Caddy was really good, and me beating him probably is more reflective of the cars than the drivers. A couple other cars were ill-equipped for the conditions (a few with all-seasons tires, and an RWD Porsche with snows, but they were super low profile).

My best success of the weekend by far, however, was the two friends I convinced to join me. A friend and her b/f went in her '21 Outback XT. They had a hard time on day 1 b/c they couldn't fully turn off the stability control, and b/c her Nokian WR G4's, while decent legit 4-season snow tires, weren't as good on the ice as anyone that had stud-less or studded ice tires. On day 2, I offered to let them take Molly, and I took the Outback, for the first half of the day. That changed everything for them. She got over her fears of deliberately throwing the car into a slide. By the end, she was hanging the tail out like everyone else, slamming the accelerator on the straight (to the point where she schooled me, and I realized I was being a pansy there!). She was even doing donuts by the end and reveling in them. She had been hesitant to go to the course at all - but when it was over, she was literally bouncing up and down, saying "When is the next one? When can we do this again??!!"

 

[JohnnyMac_]

Hello everyone,

I've just returned from Winter Driving School, now that my MYP has track mode. I thought I would share the settings I came up to optimize track mode for high performance driving on snow (high performance here refers fine control, not outright speed).

Here's a video - see below for discussion of settings & analysis.

Before my MYP, I had Audi's and Subaru's that would let me turn off the stability program. That was much more effective in snow than an MY without track mode. I had hoped they'd eventually give us track mode, and that with it, my MY would be able to get into the same ball park for car control as my prior cars. I am happy to report that that is exactly what happened - but it was not a direct, or short path to that goal. If you just want to know the numbers I'll give the spoilers now. Read on if you're interested in why these ended up being the right numbers or in how we got to them.

Notes:

• These settings were with around 200 lbs of cargo in the trunk
• The track had a solid foundation of ice with several inches of snow that we wore through in several spots.
• These bias and regen settings are likely not optimal for either all-ice or all-snow, but they'd be fine as a starting point
• The stability setting is critical, and would be the same for any conditions

Settings:
Front/rear power bias: 30/70% (anywhere between 35/65 and 20/80 was acceptable)
Stability: -9
Regen: 75% on the skidpad, 30-40% on the slalom

IMPORTANT: Watch out for ABS on ice - with regenerative braking on even partially, if you trigger ABS, the car will keep doing ABS after you take your foot off the brake, b/c it still does ABS for regen-braking. That means you can't threshold-brake to get back your grip. Or at least to do it w/ regen on, you would have to actually press the accelerator to the point where the car wasn't braking anymore, reverse-modulate by lifting to brake more, and pressing to brake less. Crazy-making, that was too next-level single-pedal driving for my brain, I didn't try.

Ok, I'll jump directly to the biggest spoiler from all that: the -9 stability setting. It took a lot to get to this.

-10 does not work well because the MY has open differentials, and uses the brakes to force power from a slipping wheel to the other side of the differential (some call this EDL - Electronic Differential Locking). However, Tesla considers this part of "stability," and when stability is at -10, it's completely off. -9 is the magic number because it enables just enough EDL to reliably get wheels on both sides of an axel to spin together, without cutting out power or doing other tricks to stop you from sliding intentionally.

Here's how we came to all the above...

On the first day, my results were really frustrating - about 1/3 of the time, I could initiate controlled oversteer readily, and keep it controlled for 3-8 seconds. 1/3 of the time it wouldn't come easily, I'd have to slam the accelerator to get oversteer, and then it would be wild/uncontrollable. And 1/3 of the time the car just wouldn't do anything except just keep going slowly in whatever direction I was pointing it, with no understeer or oversteer, no matter how hard I pressed the accelerator.

I tried many combinations of settings that day, ranging from 50/50 to 20/80 bias, 30-80% regen, and -10, -7, and -6 stability. The other tweaks only had a minor impact on how often or how long I could maintain controlled oversteer, or how likely I was to wildly oversteer & spin out. There was no happy medium - always a split between too much, not enough, and always unpredictable.

We had a social event that evening, and I had a great super technical conversation and super constructive conversation with one of the instructors. We had several theories:

1. Maybe even with stability as low as I can put it, the car is still doing some stability control
2. Maybe there is a timer, and it's only willing to let me spin wheels wildly for a limited time
3. Maybe part of the problem is that when the details are just right, and open differential can still spin both wheels (like if they have exactly the same amount of grip and are going the same speed when you overpower them)
4. Maybe the built-in "Drift Mode" setting - which you can not edit, but you can see what settings it is using - has a hidden change that it does that is not available to me in the custom settings

So, we came up with the following experiments to answer the above questions, and he let me go out to the track early on day 2 to conduct them:

1. Get on some ice, point the car straight, and floor it for a long time. See if it eventually cuts power
   1. It did not
2. Same as above, but have observers on both side of the car - see if all four wheels are spinning at the same time
   1. They were not. Sometimes wheels on both sides of an axel would spin, other times it would go back & forth between one side and the other.
3. Turn on Drift mode, and see if I was maintain a continuous drift without it ending except by my choice
   1. I was
4. Duplicate Drift mode's settings in a custom setting group, and see if I was still able to maintain continuous drift (thus proving or disproving whether the built-in Drift mode has a special hidden setting)
   1. I was, and thus, it does not.

Armed with all of the above information, the instructors all concluded that the car still has some kind of traction or stability control going on, even when it's set to -10. I was not convinced. The one thing we didn't have an experiment for was to determine whether the inconsistent results were simply because an open differential has inconsistent behavior.

That is when I thought of trying -9. It was more of a hail-mary, I never believed it was going to work. My thinking was this:

• If an open diff sometimes will still spin both wheels, then maybe all the times I was able to cause oversteer, it is because in those cases, by chance, I got both wheels to spin.
• I had a feeling that the alternating spinning and stopping of wheels that they reported during the straight-line acceleration test was because as I moved forward (slowly b/c of all the slipping), a wheel that was once on ice would eventually find snow, and if the opposite wheel was then on ice, I'd expect the slipping to switch from one wheel to the other
• Maybe, with a lot of luck, if I add the smallest amount of stability programming that I can add, it will bring in just enough EDL to force both wheels to spin whenever one is spinning, but not so much as to prevent me from getting the car to slide.

Well it worked! We did one more test:

• Straight-line floored acceleration with observers on both sides, and front/rear bias at 50/50
  • All four wheels spun continuously until I took my foot off the accelerator!

After that, I tried 25/75 front/rear bias and hit the skid pad again. For the first time, I was able to "drift" in all-wheel-drive mode for as long as I wanted, and it worked every single time. We never did bother to figure out why Drift Mode also enabled this, even though it uses a Stability setting of -10. I think it is a combination of me already being moving and turning before flooring it, and turning off the front motor means the equation for keeping wheels on both sides of the read differential became much simpler.

View attachment 902093

Great insights - thank you ))

 

[avramd]

Slip Start got the car moving slightly so I just rocked it back and forth between D & R while flooring it until the car was able to back out of the pile of snow.

I just re-read your post, and this jumped out out me. I seem to have missed this before. Do you mean you just kept the pedal on the floor constantly while switching between forward and reverse?

Maybe that is how slip-strat is meant to be used. I would have expected that the car wouldn't let me switch from forward to reverse while the pedal is pressed more than a little. My experience of slip-start is that it would give power at first, but quickly give up. Huh. Wish I had seen this when there was still snow on the ground...

 

[gx9901]

I just re-read your post, and this jumped out out me. I seem to have missed this before. Do you mean you just kept the pedal on the floor constantly while switching between forward and reverse?

Maybe that is how slip-strat is meant to be used. I would have expected that the car wouldn't let me switch from forward to reverse while the pedal is pressed more than a little. My experience of slip-start is that it would give power at first, but quickly give up. Huh. Wish I had seen this when there was still snow on the ground...

I guess I wasn't very clear with my description. I meant that I alternated between shifting into D and flooring in then shifting into R then flooring it. I can see how what I wrote read like I was flooring it the whole time while alternating between D & R.

 

[avramd]

I guess I wasn't very clear with my description. I meant that I alternated between shifting into D and flooring in then shifting into R then flooring it. I can see how what I wrote read like I was flooring it the whole time while alternating between D & R.

Ok, got it. Are you able to do this continuously, quickly, without hitting the brake in between?

I couldn't find a rhythm that worked like proper rocking in a manual ICE car. I don't remember what the issue was. it was one or both of the following:

• The car refused to shift gears without me being on the brake in between,
• I had to brake to capture the gains of each rock, b/c the car would settle either while I was trying to shift, or b/c the power would cut out.

It was extremely tedious and slow.

 

[gx9901]

Ok, got it. Are you able to do this continuously, quickly, without hitting the brake in between?

I couldn't find a rhythm that worked like proper rocking in a manual ICE car. I don't remember what the issue was. it was one or both of the following:

• The car refused to shift gears without me being on the brake in between,
• I had to brake to capture the gains of each rock, b/c the car would settle either while I was trying to shift, or b/c the power would cut out.

It was extremely tedious and slow.

I don’t recall if I hit the brake between shifts, but I basically tried to rocked the car like I would if it was an ICE. It took some work to get out of the snowbank, but I was happy to find out that the car was capable of it.

 

[Cooker]

Many thanks OP, this will be helpful if and when we get snow here. My current Model S 75 RWD is utterly useless in any level of snow and ice, but I love RWD driving feel in normal conditions and it's awesome with the staggered 21" wheels in the dry.

I have a MYP on order. I'm thinking of using track mode for a 'sport Mode' driver profile wherein I'd keep stability settings at 10, but change the power delivery ratio to a heavier RWD bias.

Question1: can you save a driver profile with track mode?

(I mean regular profile that saves the track mode config. that was last used so that I can switch between regular no track mode driving and the RWD bias mode). I appreciate the Tesla advice not to use track mode on public roads, but in this use case I'm prepared to take that risk wrt. warranty and insurance.

Question 2: what is the 'normal' (non-track mode) power delivery ratio between front and rear? Is this variable based on speed (I heard a long while back that on highway and at cruising speed the front motor is used more unless accelerating as it's more efficient)

Hope you don't mind the long post and questions...so excited to get this car in a few weeks!

 

[kpanda17]

Many thanks OP, this will be helpful if and when we get snow here. My current Model S 75 RWD is utterly useless in any level of snow and ice, but I love RWD driving feel in normal conditions and it's awesome with the staggered 21" wheels in the dry.

I have a MYP on order. I'm thinking of using track mode for a 'sport Mode' driver profile wherein I'd keep stability settings at 10, but change the power delivery ratio to a heavier RWD bias.

Question1: can you save a driver profile with track mode?

(I mean regular profile that saves the track mode config. that was last used so that I can switch between regular no track mode driving and the RWD bias mode). I appreciate the Tesla advice not to use track mode on public roads, but in this use case I'm prepared to take that risk wrt. warranty and insurance.

Question 2: what is the 'normal' (non-track mode) power delivery ratio between front and rear? Is this variable based on speed (I heard a long while back that on highway and at cruising speed the front motor is used more unless accelerating as it's more efficient)

Hope you don't mind the long post and questions...so excited to get this car in a few weeks!

I am unsure, but look into the SEXY macro buttons to help with these quick setting changes

 

[gx9901]

Many thanks OP, this will be helpful if and when we get snow here. My current Model S 75 RWD is utterly useless in any level of snow and ice, but I love RWD driving feel in normal conditions and it's awesome with the staggered 21" wheels in the dry.

I have a MYP on order. I'm thinking of using track mode for a 'sport Mode' driver profile wherein I'd keep stability settings at 10, but change the power delivery ratio to a heavier RWD bias.

Question1: can you save a driver profile with track mode?

(I mean regular profile that saves the track mode config. that was last used so that I can switch between regular no track mode driving and the RWD bias mode). I appreciate the Tesla advice not to use track mode on public roads, but in this use case I'm prepared to take that risk wrt. warranty and insurance.

Question 2: what is the 'normal' (non-track mode) power delivery ratio between front and rear? Is this variable based on speed (I heard a long while back that on highway and at cruising speed the front motor is used more unless accelerating as it's more efficient)

Hope you don't mind the long post and questions...so excited to get this car in a few weeks!

You have to activate track mode each time you want to use it, and it can only be turned on when you are parked and have stepped on the brake pedal. You can turn it off anytime though. It does not come on by default with a particular driver profile. When you activate track mode, it does use the last track setting you used.

The normal power delivery of MYP is rear wheel drive. It would engage the front wheel as needed depending on the situation. You can't turn off stability control when not using track mode, so the car would intervene during aggressive turning in normal driving. When you adjust the handling bias in track mode, it adjust the power delivery during turning. Going in a straight line it still uses mostly rear wheels in track mode unless you're mashing on the accelerator pedal. I have the S3XY button app that displays front and rear inverter output in real time, and there isn't much difference going in a straight line whether or not I'm using track mode.

I love that the MYP got track mode, but I've only really used it on an HPDE track because it's not really practical to use in everyday driving. For starters, the battery cooling fans come on full blast when track mode is turned on, so you have extra noise and potential wear and tear on the fans if you use it too much. I also think you would need to be driving pretty aggressively to notice a difference, but I'm not much of a performance driver, so perhaps I don't know what I'm talking about.

 

[buddhafree]

Question1: can you save a driver profile with track mode?

(I mean regular profile that saves the track mode config. that was last used so that I can switch between regular no track mode driving and the RWD bias mode). I appreciate the Tesla advice not to use track mode on public roads, but in this use case I'm prepared to take that risk wrt. warranty and insurance.

Question 2: what is the 'normal' (non-track mode) power delivery ratio between front and rear? Is this variable based on speed (I heard a long while back that on highway and at cruising speed the front motor is used more unless accelerating as it's more efficient)

Hope you don't mind the long post and questions...so excited to get this car in a few weeks!

1. You can create and save track mode profiles with custom settings. You have to be stationary to enable track mode.
2. Normally the car tries to use rear motor as much as possible to save energy. During accelerations or if system detects slippery road then it engages front motor. Off road mode keeps around 50/50 power between front and rear all the time.

 

[Cooker]

1. You can create and save track mode profiles with custom settings. You have to be stationary to enable track mode.
2. Normally the car tries to use rear motor as much as possible to save energy. During accelerations or if system detects slippery road then it engages front motor. Off road mode keeps around 50/50 power between front and rear all the time.

Thank you. So these are track mode, not driver profiles, accessed only when you (each time) go into the menu and turn track mode on. So you cannot store a driver profile in the main driver profiles list that maintains track mode as the default each time it's seleceted? This would make sense, just not supportive of my use case. That said, your response to Q2 is interesting. I thought that for highway crusing the fronts were used as more efficient and rears kick in when accelerating.

All ends up, doesn't look like I can manually set a more RWD setup for everyday usage unless I do so each ride in TM settings....which isn't very difficult...3 clicks away

 

[buddhafree]

Thank you. So these are track mode, not driver profiles, accessed only when you (each time) go into the menu and turn track mode on. So you cannot store a driver profile in the main driver profiles list that maintains track mode as the default each time it's seleceted? This would make sense, just not supportive of my use case. That said, your response to Q2 is interesting. I thought that for highway crusing the fronts were used as more efficient and rears kick in when accelerating.

All ends up, doesn't look like I can manually set a more RWD setup for everyday usage unless I do so each ride in TM settings....which isn't very difficult...3 clicks away

Correct. You have to go to track mode to choose your custom profile each time.
There is one inconvenience with track mode when used in regular driving. The navigation is off when track mode is enabled. Instead it shows you map specifically designed for track use. It's great for track use but not helpful for normal driving. I have to use my phone GPS for directions. I wish there was a way to switch between navigation and track map when using track mode.

 

[kpanda17]

Thought SEXY buttons can do it

 

[avramd]

Question1: can you save a driver profile with track mode?

Someone else already gave you the primary answer & pointed out the drawback of not having access to navigation. I vaguely recall that there are other features that are unavailable when in track mode, but I don't recall what they are. The obvious one is that without navigation you lose charge planning. You could use ABRP, but AFIK that can't get real time data to learn that energy usage is not as predicted, and update its plan. That could be a real problem since if you are driving in a way that benefits from track mode, default range estimates are probably way off.