Why does my Audi A2 have low fuel economy?

I've noticed that my Audi A2's fuel economy is significantly lower than the advertised figures. What could be causing this issue and how can it be addressed?

One potential reason for your Audi A2's low fuel economy could be a dirty or clogged air filter. This can restrict the flow of air into the engine and cause it to use more fuel than necessary. Consider replacing the air filter every 30,000 - 45,000 miles to improve your A2's fuel efficiency.