[BrianG]

The main hurdle I think would be to physically fit everything on one chassis. Then, there is the cost/hassle to benefit ratio. But that aside, since we are just talking about concept, how's this:

Take a look at any electric start nitro setup (Trx Revo/Jato/etc, Losi TenT, etc). They have an electric motor that starts the motor right? Well, remove the OWB, beef up the "transmission" (gearbox connecting the electric motor to the engine), and install a proper size BL motor in place of the small brushed motor.

Then, have additional circuitry to detect when the engine is running at a certain RPM, and use that to cut the power going to the electric motor, and then pull power from it instead so it'll function like a generator/alternator to recharge the battery. That's gonna take some special ESC hardware to do that if you stick with brushless. For the sake of simplicity and time, I'd stick with a brushed setup. So, use one of the larger motors like the one used in the Summit, Kershaw 700 Revolver motor, etc. Essentially, the nitro engine would be the primary power plant and the electric would provide assist on startup and low speeds.

Any other setup will probably require LOTS of custom parts. Not sure how crazy you want to get with that though.