In the New Blog: Driving Range for Model S Family.... thread there was talk of how the future "torque sleeping" (resting second motor while coasting) works. This gave me another idea, that I'd like to hear your thoughts on. How many of you are familiar with how e.g. Haldex multi-plate clutch operates in some four-wheel drive ICEs like some cars from the Volkswagen group and Volvo. There are some variations of the concept based on generation (later ones are not as limited), but basically the idea has been that it sits on the axle and activates the rear only when front detects slippage - otherwise driving the car as a front-wheel driver. I wonder if a similar economy mode for P85D or even 85D (in the latter case they could choose either motor) might be preferable for some people. Of course that would open the driving dynamics to certain inherent weaknesses, the AWD would loose some of its predictability (Haldex cars are not always the most pleasant to drive) and the car would get some of the hallmarks of front drivers like pushing, but the rear motor would activate only when the front is slipping and thus save energy more often than just when cruising. Now, of course, the unique feature for such an economy mode in a D Tesla - compared to the average Haldex car - would be loss of power, because the front and back doesn't share an engine, but are run by separate motors. The rear suddenly powering on slippage would have to be regulated so that the car doesn't rocket away unpredictably. Maybe there could be a curve where both slippage and major acceleration would always ask for the rear too, while suitably gentle driving in low-slippage conditions would only run the front. Anyway, given that Normal mode probably is the one with "torque sleeping" for coasting only, while Sport and Insane run the fuller gamut of the two motors, there could still be room for an Economy mode that would instead maximize the use of a single, economical motor and rest the rear as much as possible. This would not make for the most compelling driving experience, but it could result in some pretty nice EPA ratings and be a sort of second "range mode". Just speculating of course. What do you think - or perhaps has Tesla discussed such an option already?