Well, I don't know about a full-blown "hybrid"...but the idea of a turbo gas or diesel powered/electric drive vehicle is appealing.
A much smaller propulsion battery and the loss of a crap-load of needless computerized garbage would make a much better vehicle.
When electric motors replace the transmission, clutch, transfer case, differentials and drive shafts, a whole lot of mechanical things to wear out, or break, goes away.
Using the motors as brakes also works, but the term "regenerative" doesn't quite work yet as the technology doesn't exist yet to allow the batteries to absorb the braking energy (maybe if you were descending the Continental Divide)
So my proposal would be:
In a vehicle of any size, a smaller storage-cell/capacitor "battery" to provide supplemental "juice" for starting from a dead stop and instant acceleration.
A smaller displacement, but high output turbo engine that would give you all the on-demand power for acceleration, lugging and towing. It would revert to a preset "best efficiency" RPM once cruising speed was attained.
Four motor/generators, one at each wheel to provide, all wheel drive, electric braking, and traction control.
It would need no gearboxes nor big axles, so none of that would be there to; add a lot of weight, get hung up on off-road obstacles, or wear out. As an additional consequence and benefit, ride height/ground clearance could be completely adjustable.
You could take it out in the rocks all jacked up, raise or lower one wheel if you wanted to to level it off or get some traction, then when you were done, you could get back out on the highway, and take it up to 80, just barely clearing the pavement.
Actually, the regeneration works quite well. In a car with a charge indicator, you can see the battery charge significantly with moderate braking at typical city cruising speeds.
The batteries can't absorb all the energy, due to the mechanical, electrical, and chemical losses. But, it's enough to provide at least some of the subsequent acceleration.
A smaller displacement, but high output turbo engine that would give you all the on-demand power for acceleration, lugging and towing. It would revert to a preset "best efficiency" RPM once cruising speed was attained.
This is what hybrids do -- they are programmed to run the engine at best efficiency and either supply needed torque from the electric motor, or channel excess engine power into the generator to charge the battery.
And some of them have high-output turbo engines that are smaller than would be needed without the hybrid systems. The BMW i8 has one, although it's certainly an expensive model.
Four motor/generators, one at each wheel to provide, all wheel drive, electric braking, and traction control.
I don't know if any car has four motors, but there are several with three: a single drive motor/generator on the engine transaxle, and one on each of the remaining wheels.
In the case of the Acura RLX Hybrid, the real wheels are differentially driven or retarded with positive or negative torque, and assist in turning the car at lower speeds.
The AWD Tesla's have one motor/generator for each pair of wheels.
I realize you are actually referring to a fully electric system that decouples the engine from the drivetrain, like a diesel-electric locomotive. The early models of the Chevrolet Volt operated like that most of the time. But, it still had a mode that would clutch into the drivetrain in certain circumstances. And, the 2016 Volt eliminated that in favor of a new system that acts like most hybrid systems: when the engine is running, it provides some torque to the drivetrain.
Perhaps an engineer can explain exactly why no one has gone to a pure electric drivetrain. I suspect it has something to do with delivering maximum horsepower to the wheels when the battery is depleted -- there will be a significant loss in the electrical system without the direct coupling.
And due to that loss, highway cruising will require more power than if the engine is providing it direct to the transaxle, resulting in lower gas mileage.