A mild hybrid is a type of hybrid vehicle that uses a small electric motor and battery to assist the internal combustion engine (ICE) in certain situations, such as accelerating from a full stop or coasting. The electric motor is generally an integrated starter/alternator, sometimes known as a generator-motor unit, that provides greater efficiency through the use of a single device. Mild hybrids do not have an electric-only mode of propulsion, and the electric motor is not powerful enough to drive the vehicle on its own.
Mild hybrids are generally cars with an ICE equipped with a negligibly bigger electric combined motor and generator in a parallel hybrid configuration, allowing the engine to be turned off whenever the car is coasting, braking, or stopped, and then quickly restarted once power is again required. They may employ regenerative braking and some level of power assist to the ICE, but they do not have an electric-only mode of propulsion.
Mild hybrids are a relatively inexpensive and fairly simple way to improve fuel economy and reduce emissions compared to full hybrids or plug-in hybrids. They are finding their way into a wide range of vehicle classes and manufacturers, including Audi, BMW, Cupra, Fiat, Ford, Jaguar, Kia, Land Rover, Seat, Suzuki, and Volvo.
