Why is the fuel consumption in my Audi A2 higher, even though I've been driving conservatively?

Lately, I've noticed that my Audi A2's fuel consumption has increased significantly, even though I've been driving carefully and not using the AC as much. What could be causing this sudden increase in fuel usage and how can I reduce it?

First, make sure to check your tire pressure regularly. Low tire pressure can significantly increase fuel consumption. Also, try to avoid idling for long periods of time and use cruise control when possible.