Economy mode for "D"? Running one small motor only, unless exceptional circumstances

[RDoc]

I suspect they can turn motors on from 0-100% with no perceptible "shock" since they're completely computer controlled. Why would the regen be unavailable, and what do you mean that regen helps keep the axle on the road?

I also suspect they will use differential left/right braking in addition to front/rear torque splitting to achieve better 4 wheel traction control.

What would be really interesting is if they could use all that to also tighten the turning circle. Strongly brake the rear inside wheel, mildly brake the inside front wheel and drive the outside front wheel faster than the outside rear wheel. There'd be some scrubbing, but if this were only done on very tight turns I wouldn't think there would be any appreciable wear.

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I had another, perhaps crazy, thought. Assume that on the 85D (non P), the gearing and motors are the same as has been reported. In that case, perhaps for a slight efficiency gain, the car could cycle back and forth between the two motors on the highway so each would stay cool. Run one till it starts to warm up, then switch to the other, etc. This would be a bit fraught if the car weren't running in a more or less straight line, but for highway travel, where efficiency is an issue, it might help.

I'm not sure though that the pitch of the car would remain constant with the torque moving from front to back though. That may be an argument for using the front motor alone on the highway since the nose of the car might lift less to counter the torque on a coil sprung car. For an air suspension the car could compensate.

 

[GSP]

If I understand the OP correctly, his suggested "Economy Mode" would be:

1) another drive mode in addition to the promised "normal" "sport" and "insane" options
2) only one motor would be used, regardless of the driver's torque request, even at WOT
3) however if tire slip was detected, then the second motor would be used to provide AWD traction. Perhaps this would only happen if torque was low when slip was detected, indicating a slippery surface.

This would provide much reduced performance, and would not help range unless the driver uses enough pedal to activate the second motor in normal (”sleep") mode. It could be useful, depending on how easy it is to achieve the same result by just being light on the accelerator.

GSP

 

[3mp_kwh]

I think the OP means a driveline that would detach one of the motors (aka Haldex). The idea you honestly wouldn't feel these motors engaging tells me "idled" means both motors are always rotating at their respective single-geared speeds. They are never clutched out, or in neutral. If you spin the motors on display at Tesla's stores, its clear there is seemingly no friction in their spin. But they are heavy, and their rotational inertia is something you can also feel, in spades. It follows that single highway speeds can be efficient, but the parasitic drags of changing speeds, and constantly beating that inertia, is what to me sounds like the big challenge. S85D, if it achieves 5 better miles of EPA AER (270 per blog), will on the one hand be harvesting better efficiency than S85 because of its small motor, but it will also be fighting significantly more "idled" mass. That's because, as mentioned, the "hubs never unlock". The smaller S85D motor may be able to achieve ~280 on its own, but what is implied to me is that it might lose 10 because of the permanent connection.

If you don't get the added mass out of the driveline, there is no amount of digital programming that reaches the same effect as one smaller motor.