Why is the engine of the Audi A4 so efficient?

I have heard a lot about the Audi A4 having an extremely efficient engine, but I am not sure why. Can anyone explain the specific features or technologies that make the engine so efficient?

The Audi A4's engine is equipped with a turbocharged 4-cylinder engine, which allows for more power and torque while using less fuel. This is achieved through the use of direct fuel injection and variable valve timing.

Another reason for the Audi A4's efficient engine is its lightweight construction. The car utilizes a mix of aluminum and high-strength steel in its frame, reducing overall weight and improving fuel efficiency.