How can I improve the fuel efficiency of my 2003 Audi A2?

I own a 2003 Audi A2 and I've noticed that it's not as fuel efficient as it used to be. What can I do to improve its fuel efficiency?

One way to improve fuel efficiency is to regularly maintain your car. Make sure you regularly change your oil, air filter, and spark plugs.

Another thing you can do is check your tire pressure regularly. Under-inflated tires can decrease your fuel efficiency.

Avoid unnecessary idling and aggressive driving. Both of these habits can significantly decrease your fuel efficiency.