Although in the popular mind a hybrid car is a gasoline car with an electric motor, I imagine that there's some space for simplifying the design of the gasoline motor, once you have the electric once.
If you have an electric motor, you won't need a dedicated alternator, would you? I also see that the regenerative braking might reduce strain on the main brakes. On the other hand, I believe hybrids still have an independent 12-V battery, as other gasoline cars have.
What simplifications in the design are possible, once you have a strong electric motor? How would that impact maintenance cost?