There are 3 designs in the hybrid market.MildA battery and electric motor assist the combustion engine. FullThe electric motor and combustion engine work together or it can run on either alone. Braking may be used to help charge the battery.Plug-in The combustion engine is a backup to the electric motor.The 3 are a state of flux and it is yet to be determined which will be the front runner I think it will be the total electric to be successful it has to not have a conventional engine.Total Electric The total electric is a rechargeable that you plug in to recharge. Most of the charging will be done at night so the idea that we will need more power to charge them is not true as we have excess at night. You do have to have a plug installed in your house but they will run 100 miles on a charge and will recharge to 80% in 15 minutes. As more become available the charging station will also be easier to find. Battery life and price are the largest drawbacks to their future success.FYI In 1902 Ferdinand Porshe developed a hybrid, in 1997 the Toyota Prius came on the market