What does the petrol engine in an Audi A7 do?

I am buying an Audi A7 and I am confused about the petrol engine. What is its function and why is it important? Can you explain it to me?

The petrol engine in an Audi A7 is responsible for powering the vehicle and generating movement. It is important because without it, the car would not be able to function.

The petrol engine in an Audi A7 also plays a role in fuel efficiency. When the engine is properly maintained and used efficiently, it can help you save money on fuel costs.