Mines a W 2.0l gti and as others have said your mpg is way off. If I really granny drive it I can get about 42mpg if I don't get stuck in traffic. Normal driving I get somewhere between 32-37, again mainly depending on how often I get stuck in traffic. Even if I boot it (which is kind of a requirement to make the 2.0 actually go fast

) my mpg doesn't suffer too much.
Is it running okay ? Mine once went through a phase of reporting 15-20mpg and the engine was running a bit rough. It started doing this after the oil warning light came on and continued running like this for about a week after being topped up. I had it booked to go into the garage and the day before it just went back to normal. Not sure if this was a result of it going into safe mode or something ? It really was using sh!t loads of petrol too, not just reporting the mpg wrong. Needless to say the oil is checked weekly now.