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Model S and coasting, increasing the comfort for passengers

Discussion in 'Model S: Driving Dynamics' started by DITB, Nov 2, 2014.

  1. DITB

    DITB Charged.hk co-founder

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    I finally got it, while learning more and more about the car.

    "It", - you know that, lifting the foot off the accelerator, it can be hard to hit that sweet point where it's not braking, just coasting? I asked for a shortcut to toggle between low and normal regen - and got a lot of flak for even asking - but I don't need it now (the low/normal toggle)

    How many of you use Neutral, while driving? I remember reading about it previously, before I got the car, then forgot it again. It's quite useful, look at this scenario:

    Coasting, making a long stop ...

    So you can see in front of you, that you will have to stop completely further ahead. Two options: 1) Keep going, then brake (regen), or 2) regen now, then leap slowly forward? In these situations I miss the clutch in the stick-shift or the toggle to Neutral in an automatic.

    But no need, the Model S also has Neutral.

    I just couldn't make it work properly to my liking, yet as I started to test it more, I finally I got it.

    So the traffic light a bit in front of you just changed to RED and you know it will be a while before it's green again, because you have been to this place before.

    I don't want to brake and I don't want to keep the speed, I just want to coast, leaving the passengers without any jerks at all. Yes, I know regen will put power back in the battery, but it's not 100% efficient - there are times where coasting seems (to me) to be the better option.

    Clicking the lever briskly up to Neutral, it will release a triple warning tone, and it doesn't always work going into Neutral. That is because you need to toggle it just a little, NOT into R but just one small click up to N (just like when you want to add or subtract one single km/h or mph, with the cruise control). Bang, and you are gliding like a floating carpet, no bells of warning, no jerks at all. And boy does this car glide! Due to the inertia it seems like it wants to glide for a long time.

    Now the light is green, and since I didn't stop completely anyway, I want to go back to Drive - also without a jerk, please. The first thing I do is to press the accelerator just a tad down, then pull down to D again. Now this toggle requires a deep toggle, nothing will happen if you just wiggle it slightly like you did going from D to N, take it all the way down to re-engage D. If your accelerator is just a little down or so, you won't even feel the (virtual) engagement of the motor. Virtual, as we know there is no disconnect, it's all purely electronic. The idea is, I want to go back to drive, neither accelerating nor braking too much.

    Maybe it seems a bit awkward, but never mind, it works a charm. Just tried it a bit, it is so much more comfortable. Some don't care much about comfort, but when not sporting about, I really enjoy to try to drive as comfortably as possible.

    I know, I know, a lot of you guys have known this for ages, yet I am sure there are a lot of drivers out there, who haven't yet discovered this way of driving.

    Other ideas along the same lines? I found it quite useful, maybe there is an even better way?
     
  2. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    I find that getting my foot at that sweet spot of zero, no regen and no power added (or reasonably close to zero), is really not that hard and is a lot simpler and safer...
     
  3. Lloyd

    Lloyd Active Member

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    IMO the better way is to leave it in gear, and use your foot to adjust the acceleration and deceleration. That's what it was designed to do.
     
  4. DITB

    DITB Charged.hk co-founder

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    Maybe I will learn to find that some day. For now, as there is no detent, I haven't been able to master it entirely. With the method described above, the sensation of effortless and comfortable gliding is really impressive.
     
  5. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    You don't have to hit zero power perfectly. Anything close is good enough, and within measurement error of minimum energy usage. Just aim to be close and don't try too hard for perfection.
     
  6. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    I agree. If the situation were to change and you needed to accelerate to avoid an accident you won't have any power until you change back into D. Finding the sweet spot on the pedal isn't difficult.
     
  7. mkjayakumar

    mkjayakumar Active Member

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    I agree with OP. I find it so hard to keep it in that sweet spot for coasting on my Leaf, but Leaf has this amazing joy stick (aka hockey puck) which makes it a real pleasure to switch from D to N and back to D.

    And it shouldn't be a surprise that I get better efficiency by doing more coasting and less regen. Regen off the gas pedal on level ground is a nuisance.
     
  8. breser

    breser AutoPilot Nostradamus

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    As has been mentioned when this has been discussed before coasting in Neutral going downhill is illegal in many locations.

    I don't find the accelerator pedal that difficult to find the right spot to be coasting that hard. Takes a bit of practice but after a while it's quite easy.
     
  9. tezco

    tezco Sig P85

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    I never use neutral when out on the road in my Leaf, or in my S. Regen is so sleek that I can't give it up. Plus the brakes will last much longer with regen. As Cottonwood mentioned, it doesn't matter if you hit 0 right on the nose, somewhere close is all that is needed. I usually undershoot a stop with the S because regen in the Leaf is minimal, and I'm more used to that; but, no matter, if I'm coming up a little short it really is easy to press on the accelerator just a bit to fix the approach since my foot is already on the correct pedal.

    What I hate is my first stop when the battery is cold (or at 100%)--the lack of regen is always confusing. It would be nice if there was a way to dump that regen current into the pack warmer, or some other dummy load so that regen was always the same.
     
  10. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    It's really not difficult to find the close-to-zero spot. Just takes a bit of practice and you don't have to hit it right on. There's really no reason to ever use neutral while driving.
     
  11. TES-E

    TES-E Member

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    I find the 'sweet spot' easy to find and modulate to maintain a 'zero thrust' condition.
     
  12. DITB

    DITB Charged.hk co-founder

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    I am happy so many of you are so good at finding that spot so precisely, and don't mind that you have to keep your foot tensed to get nothing.

    For the rest of us, I only suggested an alternative method, for those who are interested and not aware of the option.

    Whatever boats your float.

    I have driven much more stick than auto, and maybe it's a cultural thing - coasting. I can't see the point of me having to fiddle with the accelerator to try to get close to a point of no power, when N does it perfectly, and with no effort. That was my point. Some of you might think I am doing this for every other stop I do, which isn't the case at all. It's just that some times I just want the power off, let the engine spin and not making any force at all.

    I read the part about regen is better than coasting, and I would like to disagree, it isn't always better. Regen is not 100% efficient, so if you regen, then accelerate to make up for the remaining distance, you have put power back into the battery, then taken it out again, while just leaving it coasting to reach the same distance, would have used less (for those odd few cases where it make sense to coast). Add to that the added comfort for passengers, as well as less strain on the foot.

    As I wrote, whatever boats your float, I fully respect it can be done without N, it's just not the way I prefer to do those longer stops or slowdowns.
     
  13. David99

    David99 Active Member

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    The confusion is that people are still so used to neutral being the best, most efficient, energy saving way to drive. It's far overrated that staying in neutral (or zero power state in an EV) would be the best way. The best way to drive in an EV is to use just enough power to maintain the speed you need. And once there is a red light to use just the amount of regen to bring the car to a stop at the light without having to use the brakes. It is not more efficient to coast and then use hard regen at the end.

    Someone mentioned since regen isn't 100% efficient it should be avoided. That statement just shows lack of understanding. Of course it can't be 100% efficient, maybe it's only getting 40% back, but that's still 40% that you get vs nothing!

    Here is example. You have a 10 mile road going downhill. You can set the car to neutral and roll down really fast and arrive without having used any energy. Or you can use a little bit of regen to maintain normal speed and arrive with more energy in the batter than before. It is irrelevant how efficient regen is, it always beats 'nothing'.

    In every day driving it really doesn't matter if you hit the perfect neutral or if you use a little power or regen. Obsessing over hitting the perfect neutral spot with the drive pedal is unnecessary and self inflicted stress for no good benefit.
     
  14. breser

    breser AutoPilot Nostradamus

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    Because it's not as safe. If you need power to avoid an accident you now have to shift back into drive. In a situation like that you're probably going to hit the accelerator and wonder where your power is and then realize you have to shift. That sort of time can be the difference in avoiding an accident or getting into one.

    In the case of going downhill and you're in neutral you can't use the motor (regen) to help brake the car. If your brakes were to fail and you needed to stop immediately you wouldn't even have the regen braking to help.

    I have no idea what the laws are in Hong Kong but in the states I'd guess about half the states have laws against what you're advocating for the above reasons.
     
  15. Larry93428

    Larry93428 Member

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    Good reasons are given above to leave it in D, including safety and legality. No good reason given to put it in N. ("float your boat"?)
    .
    What is N anyway? It does not separate any gears to disconnect motor from wheels.
    Is N anything other than the battery supplying power to keep the regen off? That is the same as I do with my foot.
    ~Larry
     
  16. randompersonx

    randompersonx Member

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    I have driven stick for the overwhelming majority of my life (and currently only own stick cars, as I am waiting for my P85D order).

    For several reasons, I never leave the car in neutral. In fact, coasting in high gear is more efficient than coasting in neutral, as the engine requires gas to maintain an idle in neutral, but does not require gas to maintain an idle when in gear. If I am approaching a red light, I will often do a double-clutch revmatch downshift to get some engine braking and be prepared to take off if the light happens to turn green before I come to a stop.

    At most, I might in some circumstances leave my foot on the clutch for a few seconds, but the car is always in gear, ready to accelerate if the situation calls for it.

    Neutral while driving is illegal in most places, and for good reason.
     
  17. bhzmark

    bhzmark Active Member

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    Coasting and minimizing the use of braking (whether from regen or brake pads) is the most efficient under any scenario. Braking = energy wasted. Less energy is wasted when the braking makes electricty instead of heat and brake dust, but it still loses some energy.

    Being able to switch between coasting and drive ought to be quick and easy. Too bad the only ways to do it are move around, but never quite being able to hold the sweet spot (with lots of fatiguing micro decisions) or to play with the toggle of the gear lever in and out out of neutral.

    Perhaps auto pilot will eventually have a hypermiler mode which will make full use of coasting as much as possible.
     
  18. DITB

    DITB Charged.hk co-founder

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    Well someone here understands, seems like most of the other posters miss the point entirely, reading what they think I wrote rather than what I actually wrote.

    Anyway, carry on, each can do what they want, I just wanted to mention the option to those who weren't aware of it. I am not here to convince anyone of anything, just offer information.
     
  19. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    My opinion is that using neutral is a bad idea. I get reasonable Wh/mi without doing that.
     
  20. ElectricAvenue

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    DITB,
    I think many of the posts here are missing your point. As long as you are using regen to slow your self down after being in neutral then you are driving more efficiently. When trying to keep in the sweet spot of coasting by featuring the accelerator you will be going into regen/acceleration slightly and that is where the loses occur compared to coasting.
    I have tried coasting with a smooth transition is really is not that difficult.
     

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