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AWD for Model S?

Will there be an option for AWD?

It isn't officially confirmed, however since Model X will have AWD and Model S and Model X use same platform I think it will be a future option, maybe in 2014 I guess.

I gather they've hired so me staff to work on it. Sounds like an unfinished project, therefore.

Would fit into the frunk easily

For my part, awd model s or no tesla at all (don't want the x).

AWD GenIII? Or New Roadster?

How does models become awd without a physical connection to the drivetrain?

@sbern18 - presumably the same way the Model X does -- you add a motor up front with a diff connecting the front wheels.

Personally, I wouldn't expect that for the Model S anytime soon, if at all.

Gotcha jat. So model x has 2 motors, cool...

This has been discussed at length a few times. I don't expect to see an AWD in the near future from what I have read here and at TMC. Maybe in the distant future. I wouldn't be willing to wait for it though, because it may not ever happen for several reasons.

You can do a search of the Tesla Motors forums by searching "AWD" at www.volkerize.com to get some background.

The Model S does surprisingly well in bad weather because the traction control is excellent. There is a significant advantage while driving in adverse conditions because you don't have to deal with gears shifting or delayed throttle response like you do with ICE vehicles.

We learned quite a bit about this while driving on the 21" wheels in an unexpected snow squall. We adjusted the regeneration to low to prevent any sudden hesitations. The performance amazed me. I thought that we were going to have to pull off the road but we made it over a small pass without a problem. I look forward to finding out how well the car performs with 19" all seasons on.

There seems to be conflicting info on how the S really handles in snow with even slight inclines. There is another thread here from a Canadian owner, with multiple commenters speaking of near undrivable conditions with just a few inches of snow and an uphill road.

I will just have to experience it for myself soon.

It could be due to different types of snow conditions. I think the regen settings can make a big difference.

I'm not saying it is a snow machine but it is far superior to what my RWD BMW could do with all season tires on it. I think another factor is the weight distribution. In the BMW all the weight was over the front tires.

I would love an AWD variant of the Model S. It would make an excellent car even more superior.

AWD will consume more power and will add more weight.
The whole motor+differential assembly is about 300 lbs.
The car is already heavy as it is (400 lbs heavier than a Jag XFR that is itself a heavy car).
The mileage will decrease as well, especially if it's full-time AWD.
It's already at about 200 miles of normal driving on a standard charge with the 85kWh battery pack (real-life data on 2,500 miles of driving in a comparably warm CA weather).
Frankly I'm a bit surprised with high expectations for the model X or model S awd.
The whole purpose of an SUV is that you can go places you normally don't go in your street/commuter car.
With the limited range and lack of charging infrastructure it would be yet another commuter, just bigger, heavier, more expensive and with a shorter range.
It may still make sense for someone driving on snow for several months in a year, but I think this market will be smaller than the marker for Porsche Cayenne (similarly priced), and you can actually take it places...
If the battery capacity is dramatically improved over the next couple of years, it may be a viable option, right now not so much.

Only the Performance X has the AWD option.

As for weight, the motor can be carried in your arms. Around 130 lbs, I think. Not significant, except for the placement between the wheels, improving traction.

Theoretically they could use a smaller motor/power supply combo, especially if the main purpose is in poor traction conditions. They could make it a part of the traction control system on future vehicles.

The AWD Highlander Hybrid we currently drive has motors (gas and electric) and a differential for the front wheels plus two independent smaller electric motors that only drive the rear wheels when needed to maintain traction. It works very well. It would seem that Tesla could do something similar to provide power to the front wheels when slippage is detected in the rear wheels. It would seem that this could be done without compromising the low CD of the S, thus not compromising range too badly.

@ Brian H

Wrong! Only the AWD has a Performance option, not the other way around. It is enough to scroll to the bottom of the Model X page and breathe before you post.
http://www.teslamotors.com/modelx

Correct. Pretty sure it wasn't always that way, but I may misremember the "reveal". Perhaps I confused 85kWh only with Performance only AWD.

@sergiyz, agreed to all others but

"The mileage will decrease as well, especially if it's full-time AWD."

That one I'm not at all sure. Increased weight obviously affect range and you can't change that, but if you free-roll the motor it still takes some energy to roll it (it's basically a flywheel then), especially in changing speed, and if you use both motors both are doing half the job to get car going. I don't know if car motor efficiency is higher or lower in high load situation, but I could imagine efficiency is higher with low load situation.

Also front motor in regen braking can gather more power than rear motor allowing better regen braking efficiency in stop&go traffic (also more stable braking if front is slowing down harder than rear in slippery conditions).

So that claim is unclear until we have some facts. In BEV full time AWD can increase the range, at least in some conditions.

@Timo,

The weight is one factor, but the energy consumption is another.
No matter what you do, two motors will consume more power than one.
Even if you split the load, both motors will have power losses, they are not 100% efficient.
So a more limited range is pretty much a given, just need to quantify it. I agree that without seeing the full AWD implementation including software that will distribute the load (the motors are completely independent, there's no central differential) it's hard to say how much lower the range is going to be.

@sergiyz, yes, but the power loss is fraction of power used, not constant (or at least constant component is small for electric drivetrain), and if you use half the power for both motors, then twice the same fraction for both equals same loss than one motor with twice the power.

10kW*0.75 + 10kW*0.75 = 20kW*0.75 = 15kW.

Motor efficiency plays a role there, if the efficiency is significantly altered by lower load, then two motors might use less power to get same result than one.

@Timo

Right, if we're assuming you can't get full power on both motors at the same time, i.e. you're sharing the inverter, this logic works.

I doubt the highway range would be significantly affected by the addition of the second motor. The dominate force, aero drag, would be identical. The only added negative forces would be any increase in friction for the second motor/gearbox which is presumably low in their current drive-train.

The additional weight would negatively affect the stop and go driving efficiency, but as mentioned earlier, the front placement of the motor will be an advantage in regen.

I thought I remember hearing that they were trying to exploit using two motors to make the drive-train more efficient, not less. I think the jury will be out on this until the X is on the road.

Hopefully this becomes their standard drive-train, I would be very disappointed if the next gen Roadster debuted without AWD.

Reading all this makes the $80 for chains a better deal for the two snow days a year in Seattle. Or I'll just drive my wife's volvo...

kalikgod;
One suggestion was for lower reduction ratio on the front, and transition more power there for highway cruising, etc., and let the rear free-wheel

Brian H: that would be truly awful. RWD bias for performance cars.

Cruising the hwy with FWD, starting and initial accel. with RWD, some overlap. What's awful?

@Brian: AWD performance cars are generally RWD biased, not the other way around. Think Nissan GTR, or Lamborghini. When driving through corners it makes quite a difference to the way the car feels. I like AWD, but after driving and owning a number of them my experience is as stated.


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