Why is my 1994 Audi 80 burning too much fuel?

I've recently noticed that my 1994 Audi 80 seems to be using more fuel than usual. What could be causing this issue and how can I fix it?

One common reason for increased fuel consumption in older cars is a dirty air filter. Consider having it replaced to improve fuel efficiency. - Jake

Check your tire pressure. Under-inflated tires can cause drag and decrease fuel efficiency. - Max

It could also be a problem with your oxygen sensors. These can become dirty or faulty over time, resulting in a higher fuel consumption. - Maria