How do I fix high fuel consumption in my Audi 80?

My Audi 80 seems to be using a lot more fuel than usual. What could be causing this and how can I fix it?

You may have a dirty air filter, which can decrease your car's fuel efficiency. Try cleaning or replacing the filter.

It's possible that your tires are not properly inflated, causing increased rolling resistance and therefore higher fuel consumption. Check your tire pressure regularly.

A worn spark plug can also lead to higher fuel consumption. Make sure to replace them regularly according to your car's maintenance schedule.