Hybrid electric vehicles use multiple energy sources to run, resulting in less noise and emissions. They are more efficient and eco-friendly than traditional vehicles. These vehicles have a heat engine, electric generator, motor, converter, and rechargeable batteries. Plug-in hybrids can be charged from a regular outlet. There are different types of hybrid drives: serial, parallel, and serial-parallel. In a serial drive, the electric motor powers the vehicle in city driving, while in a parallel drive, either the motor or engine provides torque. Hybrid vehicles are becoming popular for various types of vehicles, from cars to buses and military vehicles.