2019 Audi A8 - The V6 and V8 engines are equipped with mild-hybrid technology by way of a belt alternator starter (BAS) and a lithium-ion battery with 10-Ah electrical capacity, meaning that the A8 can coast at speeds between 55 and 160 km/h with the gasoline engine off and with zero emissions for up to 40 seconds. As soon as the driver steps on the gas again, the BAS prompts the smooth restart of the engine.