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Is the dual motor option worth it?
- Thread starter evJOULE
- Start date
MikeBur
ManualPilot
It’s definitely not as much range advantage with AWD than RWD that was originally intimated (about 10-15% iirc), though the fact is it’s net even to about 5% advantage on p85d. The p cars I would imagine should have the most difference because of the large rear motor and standard sized front motor- regular D cars have same-sized motors front and rear, though I believe there was a slight gearing difference.
The motor and additional wiring loom also accounts for a lot of additional mass and would affect numbers. The best comparison was same car and limiting to cruising at various speeds...
I did some tests a while ago using high resolution CAN bus data on when range motor chooses which motor based upon speed (all other factors (weather, temp, road type, topography, etc being equal)).
Chassis CAN Logging To ASCII Text Plus Graphing
Range mode for p85d favored front motor up until some point between 70 and 80 mph. Iirc it was about 75 though can’t find that data.
The tests in those links (particularly second one) was comparing range at cruising speed of 75mph VS 65mph. As well as the obvious increased energy overall, this be causing additional efficiency issues due to being on the rear motor at this higher speed.
Net:
If you cruise on freeways between 50 and 70 mph, a dual motor car will give you the best efficiency possible. If you have a lead foot, or cruise at higher speeds than that then the difference will be negligible.
I would assume AWD is a safety feature for better handling at similar, to marginally better, energy use.
Phew!
. Hope this helps.
The motor and additional wiring loom also accounts for a lot of additional mass and would affect numbers. The best comparison was same car and limiting to cruising at various speeds...
I did some tests a while ago using high resolution CAN bus data on when range motor chooses which motor based upon speed (all other factors (weather, temp, road type, topography, etc being equal)).
Chassis CAN Logging To ASCII Text Plus Graphing
Range mode for p85d favored front motor up until some point between 70 and 80 mph. Iirc it was about 75 though can’t find that data.
The tests in those links (particularly second one) was comparing range at cruising speed of 75mph VS 65mph. As well as the obvious increased energy overall, this be causing additional efficiency issues due to being on the rear motor at this higher speed.
Net:
If you cruise on freeways between 50 and 70 mph, a dual motor car will give you the best efficiency possible. If you have a lead foot, or cruise at higher speeds than that then the difference will be negligible.
I would assume AWD is a safety feature for better handling at similar, to marginally better, energy use.
Phew!
. Hope this helps.
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Found a P85 loaner skittish on even dry freeway on-ramps.
Found an 85D in the rain and snow as secure and "planted" as JPP said above. First week with the car found us in 6 inches of surprise Memorial Day Weekend fresh up at Mammoth, and we did better than the SUVs and pickups we saw sliding around.
Agree with others' comments that M3 RWD is surprisingly comfortable in the wet. Nicely implemented traction control.
Even did superbly extracting itself from an icy parking spot up near Mammoth in January.
Nonetheless would have felt more secure with AWD had the spot been black ice or deep snow, steeply inclined, and with the most slippery surface under the rear wheels.
Besides, although chain controls here in California tend to be strict, all-seasons (M+S) and AWD get you waved through in all but the direst of conditions.
So, if the Sierras continue to pile up March snow at a feet-per-day pace, we will probably take our 85D skiing next week, despite its shorter range and increased Supercharging time (equal kWh/min = fewer miles/min).
Definitely waiting for AWD on our second Model 3. Hope it's soon!
I live in Texas so snow is not the issue, we are currently on our second and third Teslas and are definitely waiting on the AWD variant of the 3. We test drove a RWD MS (P85+) and I found that from a stop or on wet streets it was really easy to make it loose grip of the rear wheels as well as the annoying intrusion of the traction control light and the modulation of power. I was lucky as I was able to opt for the P85D when it came out and we currently have an X90D and P100D for over the last year. I have found the dual wheel drive variants to be much more sure footed, planted and never loose traction in the wet or with spirited driving. I think that with the instant torque that the cars can put down for me the dual configuration is the ideal drivetrain.
MikeBur
ManualPilot
FYI - can only find gear ratios on p85d from original answer @sorka gave Chassis CAN Logging To ASCII Text Plus Graphing
After reading both articles over several times, something still doesn't add up to me. On the one hand, the author seems to question Tesla's claim that the dual motor increases range. The reasons he gives are based on what is known about increasing weight and friction forces and how it affects fuel economy, which makes a lot of sense to me. He then adds multiple references to real world experience which according to him contradicts Tesla's claim of increased range. He seems to get stumped though when he looks at the EPA ratings. While he does seem to have problems verifying the suggested rated ranges, no matter how you cut up the numbers, the dual motor still drove 5 miles further on 9kWh less energy according to the EPA tests.
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Right-- My S90D is rated at 103 MPG (e) and the rear-wheel drive version of same car was rated at 87. So, 18% more range for the AWD.
I put my Model 3 reservation on HOLD because I want AWD, standard battery, and don't need the upgraded interior for $5000 more.
I want AWD, even in the Los Angeles area, because it is better. It allows for more efficient traveling. Witness the 18% greater federal government agency ratings (EPA) for AWD versus the back two wheels only.
The reason I bought 2 Teslas and am buying 2 more is because it is the best car on the planet-- the most efficient auto. And AWD is another step in that direction.
Go Tesla!
RedOctober
Member
I will show my wife your post. I want a second one and she keeps saying “you already have one, want do you need another one”. My answer is because I’m getting rid of my ICE car for one and they are fun to drive.
MikeBur
ManualPilot
This is a key point. Though I don’t believe the variance in battery capacity is anywhere near 9kWh between 85 and 85D, I would be unsurprised if there were different algorithms applied to pack buffers at different times / in different firmware.
Irrespective, even if this were exactly the same available battery capacity then there is still ~2% additional range for D. My own measurements is that this is closer to 5% which would be true if there were another kWh or so in buffer for D vs non-D.
Of course we are comparing D vs non-D Teslas here. It is still amazing to me that an AWD car has as good economy as a RWD car based on traditional thinking, ie additional mechanical overhead
Vern Padgett, thanks for your insight. I couldn't be more in-tune with your enthusiasm. Mine might be a little more general as in, Go EV go, but I love Tesla, their vision and the products they make. Years ago, I remember watching "An inconvenient truth", and was amazed at how many people didn't get it. Today I can watch "Before the flood", and be no less amazed at how far we have come, but how many people still don't seem to get it. But my quote of your previous post above is actually the reason I started this thread. The 18% suggested seems to be convincingly contested, if not outright questioned. Living in Canada, I think the AWD is probably a necessity for us anyway, at least for my wife's car. She currently uses an X-drive, and being the driving force of the change in our family, I would hate to have to deal with her dissatisfaction when it comes to her comfort zone on winter roads. To me, taking the decision to go electric is an all in decision. I will have no fall back car. My purchase decision will be based on the premise that the EV car I drive is capable of replacing my ICE. In this regard, range is king for me. When I take into consideration cold weather driving, other possible variations in energy consumption due to wind and rain, availability of charging infrastructure, recharging times, and keeping min-max state-of-charge to optimize battery life, even the 310 mile LR Model 3 is at the low end of range capability IMO. Adding wheel covers and lowering the suspension are things that I would probably do upfront. So more then anything else, I just really wanted to know what real world experience this forum could offer.
Again MikeBur, thanks for all your insight, it is really appreciated. I think your quote pretty much sums up the take-away for me. Better traction and handling. As long as I am not taking a hit, if the range can be increased by even 2%, that is amazing!
It's a win-win-win. Benefits of better traction, better acceleration, and better range/efficiency. All for less than $5k. Not too shabby. These reasons are why I'm waiting for the AWD. "Late 2018" can't come soon enough for me...
Hi -- I haven't read his analysis but he might be missing the fact that each motor drives at a different reduction gearing. So the higher gearing (front motor) is probably the only one in use at speed, for its greater energy efficiency.
You all who want 4 wheel drive for snow might want to watch the now very old videos of Model S with RWD in Norway, driving on ice. TWO WHEEL ONLY DRIVE. Check this out.
You are seeing a REAR WHEEL DRIVE ONLY Tesla.
You are seeing a REAR WHEEL DRIVE ONLY Tesla.
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Sure. And probably using snow tires. RWD w/ snow tires will almost always be as good as, if not better than, an AWD w/ all-season. But we don't often get snow here, so it's not worth changing out tires for the winter. So AWD w/ all-season, just like my SUV has, will do me just fine.
EfficientWatts
Member
Even though the estimator says Late '18, my configurator says Mid '18. Anyone know the reason for the difference? That could play a big factor into my decision to get AWS or not.
ryanjm
Tesla Podcast Host
The delivery estimator is specific to your reservation, while the listing in the configurator is not (unfortunately).
Is stopping distance shorter or longer with AWD?
It is longer because of higher weight.
Do D models habe save suspension setup as RWD (front toe-in)?
I'd guess not and this is where the efficiency increase stems from.
Set the front suspension on RWD to minimal toe-in and watch the efficiency rise.
Freewheeling the motor over 1:9 gears means drag.
It is longer because of higher weight.
Do D models habe save suspension setup as RWD (front toe-in)?
I'd guess not and this is where the efficiency increase stems from.
Set the front suspension on RWD to minimal toe-in and watch the efficiency rise.
Freewheeling the motor over 1:9 gears means drag.
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