Why is the fuel economy in my Audi A3 not as advertised?

I recently purchased an Audi A3 and was excited about its advertised fuel economy of 30 miles per gallon. However, after driving for a few weeks, I have noticed that I am only getting around 20 miles per gallon. What could be causing this and how can I improve my fuel efficiency?

First, check your driving habits and make sure you are not accelerating too quickly or idling for extended periods of time. Also, keep your tires properly inflated and remove any unnecessary weight from your car. Additionally, consider getting a tune-up and using a fuel cleaning additive to improve your engine's performance.