Why is the gas mileage on my Audi A3 decreasing?

I've noticed that the gas mileage on my Audi A3 has been decreasing over the past few months. I used to get around 35 mpg, but now I am only getting around 28-30 mpg. What could be causing this decrease and how can I improve my gas mileage?

The decrease in gas mileage is likely due to a dirty air filter or fuel injectors. Both can cause your engine to work harder and consume more fuel. Try cleaning or replacing these parts to improve your gas mileage.

Another common reason for a decrease in gas mileage is a build-up of carbon deposits in the engine. Regularly using a fuel system cleaner or scheduling a professional engine carbon cleaning can help improve your efficiency.