How to get better fuel efficiency in my Audi A6?

I have been noticing that my Audi A6 is not getting the fuel efficiency that it used to. What can I do to improve it? Are there any specific techniques or maintenance tasks that can help increase my fuel efficiency? I want to make sure my car is running efficiently and not wasting unnecessary gas.

Regularly check and clean your air filter to improve your car's fuel efficiency.

Ensure your tires are properly inflated to reduce resistance and improve fuel efficiency.

Consider using a fuel additive to clean your engine and improve its efficiency.