A mild hybrid car is a type of hybrid vehicle that uses a small electric motor and battery to help it accelerate from a full stop. Unlike full hybrids, mild hybrids cannot drive on electric-only power and cannot operate in fuel-efficient, zero-emissions mode. Instead, they allow the internal combustion engine (ICE) to shut off when coasting or braking, eliminate the belt drives that an ICE requires to run certain components, and power the more robust electrical architectures that modern vehicle technologies require. Mild hybrids may employ regenerative braking and some level of power assist to the internal combustion engine, but they do not have an electric-only mode of propulsion. The electric motor in a mild hybrid provides greater efficiency through the use of a single device that is essentially an integrated starter/alternator sometimes known as a generator-motor unit. Mild hybrids can be up to 20% more fuel-efficient than the same vehicle without this type of powertrain. Some vehicles, like the new Audi A3 compact sedan, are somewhere in between mild and full hybrids. It’s technically a mild hybrid, but it’s not all that mild. As in a full hybrid, an electric motor can move the relatively small and light A3, Audi’s entry-level model, at low speeds or when coasting on flat roads.