Rikster - do you know what reg and power in the diesel you are looking for? Also If its the mk5 Golf you are on about...
If it is the mk5, then when they first came out (2005ish) the 140bhp diesels were all badged as GT's. I had a 55 plate - and it was a good motor. Can be thirsty on oil and these use a specific one too at £14 a bottle! (all of the PD style diesels are) but 50+ mpg is easily achievable. Ensure it has full service history (early ones had the 6 speed gear boxes recalled as they had a fire recall actioned) Areas to look for..The 2.0tdi's have a common failure of the lower fuel pump - you get yellow warnings on the dash telling you of this if you have a problem (VW keep loads of these in stock, tells you how common this is!) Also watch for a very noisy radiator fan (there is 2 fitted, when the main one goes, the smaller one kicks in and is obvious because its very noisy!) Engine and handling are great though, lots of torque - power is used up quickly though so they feel faster than they really are.
VW then introduced the 170bhp GT - this is a very good engine BUT lots of reported issues with the DPF filters (these are not on the 140bhp) and can cause several trips to the dealers, especially if you only do smaller journeys.
Towards the end of the Mk5, VW changed the spec from GT to GTSport for the 140bhp (removes dual zone climate / 12 speaker stereo / different alloys) from the original spec. 170bhp models became GTTdi's with the inclusion of the better alloys, dual zone climate and better stereo.
