The main common faults end up being Injector issues and Dual mass flywheel/clutch failure. Both can be rather expensive to fix. Recon injectors are about £600 a set and a full clutch/DMF kit is around the same for the parts alone.
Cracking cars though, mine has done 130,000 miles now and is still on its origional injectors/clutch and i'm not exactly easy on it.
I guess its partly the luck of the draw.
My long term fuel average according to the onboard computer is 49mpg.