I have a derv MK4 GT TDI and area's of concern have been

cam wear, ask if it's been EGR deleted if not then it may need a good clean out but you'll be able to see what MPG it's recording, wheels as a referb is going to cost £400 and caps are about £150 for a set from dealer.

Check for id plate on the fuse box cover at end of dash drivers side