I just bought my 2003 a4 1.8T quattro a few days ago, and I've discovered a problem. With a little over half a tank of gas, I drove around 10 miles and my fuel light came on, telling me I only had around 45 miles left on the tank. When I parked and restarted the car, the needle magically moved back up to half a tank. This has happened a few times now, and I'm worried that this could be a major repair that I can't do on my own. Any ideas?

hmmm, a bad ground on the needle? or maybe a sticking floater