How does the Audi A7 achieve optimal fuel efficiency?

I am considering purchasing an Audi A7, but I am concerned about fuel efficiency. Can someone explain the technology behind this car's fuel efficiency ratings and how it compares to other luxury sedans?

The Audi A7 is equipped with a 48-volt mild hybrid system, which uses a lithium-ion battery to store energy from regenerative braking and assists the engine during acceleration. This system allows the car to coast with the engine off for short periods of time, resulting in improved fuel efficiency.

The A7 also features a start-stop system, which automatically shuts off the engine when the car is stationary, like at a stoplight. This reduces unnecessary fuel consumption and emissions.