Why is the fuel economy of my Audi A4 decreasing?

I've noticed that my Audi A4's fuel economy has been getting worse lately. Even with regular maintenance and driving habits, I seem to be getting fewer miles per gallon. What could be causing this and how can I improve my fuel efficiency?

One possible reason for your decreasing fuel economy could be a clogged air filter. When the air filter is dirty, it restricts the air flow to the engine, causing it to work harder and use more fuel. I suggest checking and replacing your air filter regularly to improve your fuel efficiency.