What are common fuel efficiency issues in the Audi 80?

I've been noticing that my Audi 80 is not as fuel-efficient as it used to be. What could be causing this and how can I improve the fuel efficiency?

One common issue that can affect fuel efficiency in the Audi 80 is a dirty air filter. Make sure to regularly clean or replace your air filter to improve fuel efficiency.

Another potential cause could be low tire pressure. Check your tire pressure regularly and make sure they are inflated to the recommended level for your vehicle.

Old spark plugs can also affect fuel efficiency. Consider replacing them if they haven't been changed in a while.