All IC car engines have alternators which among other things charge the car’s conventional battery.
Of course those batteries are not then turned around and used as part of an alternate propulsion system.
How much gas mileage do you think was being lost by the need to recharge your EV Toyota Hybrid’s relatively much larger battery while driving with the IC engine?
The combined fuel mileage for the hybrid is 36MPG. Normal combined mileage for a similar ICE vehicle is 22MPG.
The regenerative braking system seem to help, also.