2018 Audi A3 Sedan / S3 Sedan — Owner's Manual
The boost function is activated by pressing the accelerator pedal farther down (kick-down). The vehicle is powered by both the gasoline engine and the electric motor when in full acceleration. Boost is only available for a short time because it uses a large amount of energy. Availability depends on the high-voltage battery charge level.
The gasoline engine switches off and disengages at speeds up to approximately 1 12 mph (180 km/h) if the accelerator pedal is not pressed and the "D" position is selected. Driving conservatively like this can reduce fuel consumption. When braking, the electric motor will act as a generator creating electric energy that is then stored in the high-voltage battery. This also occurs when the vehicle is coasting or driving downhill.
If the brakes are applied early and evenly. By doing this, a large amount of the kinetic energy is recovered and may be stored as electric energy in the high-voltage battery. The conventional brakes are also activated when the brakes are pressed very hard.