On an AWD M 3, can you chose just front or rear wheel drive?

[Rothgarr]

Pick my AWD up on Thursday, just curious if you can select to have it be just front or wheel wheel drive.

The reason I ask is because as I understand it, the LR RWD M3 is the most efficient one.

So I'm curious if you can select one or the other to extend the range and then in winter or rain I'd put it in AWD.

 

[Dr. J]

Pick my AWD up on Thursday, just curious if you can select to have it be just front or wheel wheel drive.

The reason I ask is because as I understand it, the LR RWD M3 is the most efficient one.

So I'm curious if you can select one or the other to extend the range and then in winter or rain I'd put it in AWD.

Negative, captain. The car decides whether the front motor operates, and for all I know it may be operating at all times. The rear motor is always on.

 

[Saghost]

No. But the car is smart, and it'll be using the most efficient option that's compatible with the power you're asking for and the conditions it's operating in. The AWD cars are believed to idle the front motor most of the time for efficiency.

And the AWD car still has the extra weight and rolling resistance from the front drive motor, so it'll inherently be less efficient even when operated exactly the same way, if not by much.

 

[Rothgarr]

Got it, thanks.

My current car (Suzuki SX-4) lets me choose if it's FWD only, Auto-AWD, or full AWD. That led me to wonder if there was a similar feature.

Thanks again!

 

[Dr. J]

The AWD cars are believed to idle the front motor most of the time for efficiency.

I couldn't find a source for that. Do you know of one?

 

[SleeperService]

I couldn't find a source for that. Do you know of one?

Don't have a source, but that's at least part (if not all) of the reason the front motors are still AC inductance motors instead of switched reluctance permanent magnet motors like the rear, even though the rear motors are more efficient: the inductance motors can be "slept" to free wheel, while the SR motors cannot be.

 

[diamond.g]

Got it, thanks.

My current car (Suzuki SX-4) lets me choose if it's FWD only, Auto-AWD, or full AWD. That led me to wonder if there was a similar feature.

Thanks again!

To be even more specific. The AWD 3 acts like a RWD 3 until slippage is detected, or high power output is requested. TFL did a video on it. There is also a thread here where folks have complained that it isn't full time 50/50 in the winter (can lead to rear sliding unexpectedly in some instances).

 

[Saghost]

I couldn't find a source for that. Do you know of one?

There's a lot of discussion and Tesla articles about "torque sleep" from back when the dual motor S first came around, including differences in efficiency before and after Tesla started doing it.

I haven't seen an explicit statement or test that shows the 3 AWD does that, but it seems likely, and the induction motor can be put to sleep a lot more easily and effectively than the switched reluctance motor.

The other definitive thing I do have is the AWD test from TFL, where the car started off with the rear wheels and only put power to the front when the rear slipped:

 

[Jaywlker]

Got it, thanks.

My current car (Suzuki SX-4) lets me choose if it's FWD only, Auto-AWD, or full AWD. That led me to wonder if there was a similar feature.

Thanks again!

That would be a nice feature, and probably software toggle-able, right? Someone should tweet Elon.

 

[Knightshade]

Don't have a source, but that's at least part (if not all) of the reason the front motors are still AC inductance motors instead of switched reluctance permanent magnet motors like the rear, even though the rear motors are more efficient: the inductance motors can be "slept" to free wheel, while the SR motors cannot be.

Interestingly- the refreshed Model S/X are doing exactly the opposite.

Perm mag in the front, induction in the rear.

All Model S and X vehicles now benefit from Tesla’s latest generation of drive unit technology, which combines an optimized permanent magnet synchronous reluctance motor, silicon carbide power electronics, and improved lubrication, cooling, bearings, and gear designs to achieve greater than 93% efficiency. Pairing a permanent magnet motor in the front with an induction motor in the rear

Which if it works like the 3 suggests the S/X are now.... primarily FWD? And will kick the rear motor on when the front wheels slip or more power is needed?

Which seems...weird.

 

[EVDRVN]

That would be a nice feature, and probably software toggle-able, right? Someone should tweet Elon.

There is no benefit there since the induction motor up front is less efficient and there is no traction advantage on FWD on a Tesla as the ICe is not over the front wheels. The new motor config in the S makes sense since the more powerful motor is in the rear. In the 3 it is different because the added induction motor is needed for performance and it would not make sense to have two configs in the rear as the PM is there already for the RWD.

 

[Saghost]

Interestingly- the refreshed Model S/X are doing exactly the opposite.

Perm mag in the front, induction in the rear.




Which if it works like the 3 suggests the S/X are now.... primarily FWD? And will kick the rear motor on when the front wheels slip or more power is needed?

Which seems...weird.

Pretty sure the performance cars have always been that way, since it was more efficient to put the big motor to sleep and run on the little motor. Not sure how the regular dual motor cars used to run.