Would it be possible, or even reasonable to use a 36v motor on each wheel? Then be able to switch off 2 or even 3 of them once you have reached desired cruising speed? I would think this could help tremendously in increasing range from battery pack. also would improve traction greatly with all wheels independently driven.
I’m not much of a mechanic, and its been years since I had any formal electrical or electronics training, so I am probably rehashing old or impossible ideas, but it does seem intriguing.
In theory, having four motors and turning two off once you have reached a certain speed sounds good, but there is a lot more to it. One thing that inmediatly comes to mind is that you would need a total redesign of the steering system to allow you turn and have a motor on each wheel. Also you would need a microcontroller board to be able to turn off your two motors after you have reached a certain speed. Bottom line, yes it does sound like a nice idea but once again there is a lot more to it than something most of us could handle.
I’ve thought about having 2 pancake motors on each of my rear wheels (I’m putting a 1.6L turbo biodiesel on the front axels) not so I could switch one off, but rather to have a permanent magnet (rare earth) ring turning on the axel and the brushless coils fixed on the suspension next to them. This would allow regen as well, but this also means a high end controller with variable frequency coupled to a wheel angle sensor for each wheel. I don’t know if anyone has done that…
Now, on simply shutting down motors at highway speed, they are not like an ICE where shutting down cylinders will greatly increase their efficiency - right ?
I was thinking more of conserving batteries by shutting down 2 or more motors which I guess is the same idea as shutting down cyl on ICE to conserve gas. I was thinking that it shouldn’t take as much effort to maintain speed once achieved.
Lobogris, good point about steering, I would have to think on that. How about 2 72v motors, one for each axle, with a shut-off?
Your best bet for saving energy on Steering it so convert from Power Steering to manual like I did for my project. If you were born in the 1960’s, your first cars were all manual steering 
Born in the 60’s? I wish! How about started driving in the early 60’s? (:>)) And neither my 53 Flathead Merc nor my 56Ford Vic had power steering!
[QUOTE=mtngazer;3937]I was thinking more of conserving batteries by shutting down 2 or more motors which I guess is the same idea as shutting down cyl on ICE to conserve gas. I was thinking that it shouldn’t take as much effort to maintain speed once achieved.[/QUOTE]
I don’t know how much you would save it is still going to take X number of watts to move the vehicle down the road so if you shut two motors off your current to the other two motors would double to keep the vehicle moving.
[QUOTE=arb;3944]Your best bet for saving energy on Steering it so convert from Power Steering to manual like I did for my project. If you were born in the 1960’s, your first cars were all manual steering :-)[/QUOTE]
The ratio between manual and power steering is different.
The ratio for my Manual rack & pinion is 4 turns lock to lock. For the power unit, it was about 2.8 lock to lock, thus it takes more turns to parallel park your car with Manual. But is that a bad thing ? I don’t think so.
The ratio is all inside the Rack & pinion - so the tie rods are the same, the mounting hardware is the same, the exterior is almost the same but devoid of hoses and lines to leak… the connection to my steering column is a little different, but I am changing that too.
[QUOTE=mtngazer;3954]Born in the 60’s? I wish! How about started driving in the early 60’s? (:>)) And neither my 53 Flathead Merc nor my 56Ford Vic had power steering![/QUOTE]
60’s psssshhtt it’s all about the 90’s 
Does sound like a fabulous idea; for the most part. The only issues I see with having 2x 72v motors for each axle is the differential in the back makes it act like 2 separate axles, doesn’t it? You wouldn’t be able to spin both wheels off of one point on the axle. Make sense?
[QUOTE=mtngazer;3954]Born in the 60’s? I wish! How about started driving in the early 60’s? (:>)) And neither my 53 Flathead Merc nor my 56Ford Vic had power steering![/QUOTE]
51 Ford Club-Coupe here…
Actually converting a power steering rack to manual is simple - just connect the input to output lines. Steering effort on EV cars should be a lot lighter than for your ICE powered grocery-getter if you have put a low rolling resistance tire of the appropriate load rating and profile on…
Power brakes are the other thing to think about. You may find yourself altering the pedal ratio to make manual brakes work without excessive effort.
RE: Motor on each wheel. This is done (sort of) in vehicles that have Hydrostatic drive (Large farm tractors for the most part). The only real concern I would have is Torque steer. If you lose power or have another issue with one of your motors, you could well be pulled off your intended course.
I don’t know how much battery you would actually save if you switched motors off. You will still have rotational friction losses of the freewheeling motors. If you consider it takes “x” watts to maintain a certain speed it will take “x” watts to maintain that speed regardless of how many motors are doing the work. If all motors are powered they will each take 1/4 of the load using “1/4x” each. The reason cars can achieve increased fuel efficiency is because gas engines are horrendously inefficient. Electric motors are often in the 90% efficient range with losses in bearing friction and heat. If you ran one motor 4 times as hard your one motor will heat up. As your motor heats up it will become less efficient and heat up more to overcome the inefficiency.