[Grishnakh]

No one uses wheel motors on cars; they sound good at first, but the problem is that motors are heavy, and the last thing you want on car wheels is more unsprung weight: it's very bad for ride and handling. So you still need flexible axles to transmit power from the motor to the wheels. Go look at a Tesla at the showroom and you'll see this in the bare-chassis floor models they exhibit.

Otherwise, you're basically describing the Chevy Volt. There's a reason these cars aren't more popular: they're expensive, and have a lot of drawbacks. Instead of a single drive system like the Tesla (electric motor, axles, single-speed gearbox, and motor controller, plus a big battery pack for energy storage), now you need two drive systems (the former, plus a traditional fossil-fuel engine, and a generator, and a fuel tank). All that hardware takes up space, and costs money, so you end up with a car that's a lot more expensive than a comparably-sized and appointed gasoline car. You could downsize the battery pack greatly to save cost and space and eliminate the 50+ mile electric-only range, but now you're stuck with unimpressive fuel economy: take a look at the Volt's fuel economy when in gas-only mode, it's not anything special. The Prius gets much better fuel economy than the Volt when comparing gas-only operation, and for good reason: serial hybrids are inherently inefficient because of all the power conversions. The Prius does better because it's a parallel hybrid.

Now moving away from the Volt's gas-powered piston engine to a far more compact diesel-powered rotary optimized for single-speed operation might change this equation, I don't know. Of course, as we've seen with VW, diesel has problems with emissions.

[tropo]

I still want a serial hybrid with 4 motors.

The motors wouldn't have to be unsprung weight. They could be inboard, as on the Tesla cars but in pairs. They could be inboard, tipping as needed to eliminate 1 joint per wheel. They could be out at the wheel, affixed to the body, missing the top and bottom to allow the wheel to move around them -- the car effectively being a mag-lev inside centerless wheels.

I want to not have sloppy differentials. Power to each side of the vehicle should be adjusted according to the steering input.

I don't need a battery. Give me a supercapacitor that is just big enough to handle regenerative breaking from 80 MPH to a stop, followed by running the engine while waiting for a drawbridge or freight train.

It's not about fuel economy. It's about acceleration, including 4-wheel fully independent anti-lock acceleration. It's about never feeling the jolt of changing gears, and doing so without the wimpyness of a CVT. It's about getting all this when there is no place to charge an electric car.

[Grishnakh]

If your 4-motor idea really made sense, I think Tesla would have done that. They didn't: they use a single large motor (or two, for the P85D, front and rear), driving a single-speed gearbox, through a differential, to two standard CV axles.

The Chevy Volt, too, uses a single motor. I'm not sure about the Bolt or the LEAF but I suspect they're the same.

>I don't need a battery. Give me a supercapacitor that is just big enough to handle regenerative breaking from 80 MPH to a stop, followed by running the engine while waiting for a drawbridge or freight train.

Then you're going to have lousy fuel economy. If this idea made sense, the Chevy Volt would have used it. They didn't. No one wants to buy an serial hybrid car that has crappy fuel economy. They can just buy a gasoline car for a lot less money.

>It's not about fuel economy. It's about acceleration

The Tesla P85D has this already, and without all the complexity you're proposing.

>It's about getting all this when there is no place to charge an electric car.

If you have a house with electricity, you have a place to charge your car. If you have an apartment with a parking space and no way to get power there for a charging station, then you're too poor for anyone to bother making a car like this for you.

>They could be out at the wheel, affixed to the body, missing the top and bottom to allow the wheel to move around them -- the car effectively being a mag-lev inside centerless wheels.

As an engineer, I have no idea what you're talking about here.

[tropo]

Prior to the P85D, one could have said "if a 2-motor idea really made sense, somebody would have done that". One would have been wrong to say it doesn't make sense.

Prior to the Prius, one could have said the same about hybrids. Prior to Tesla, once could have said the same about electric cars -- and at the time it was true, with nobody wanting what little was offered.

There are numerous city dwellers with plenty of money and no place to charge. Often they live in historical neighborhoods that are all the rage these days. There are also homeowners without garages, and with garages full of stuff like boats and model railroads and other cars.

Also, range anxiety is real. No, I don't want to drive along a route defined by Tesla's superchargers.

That third option for motors probably requires an animation to explain. Never mind; there are at least two other ways that work fine without the unsprung weight problem.