Always plan for 3 years but always ends up being 2 
That is usually me to a tee! There is always something better around the corner. This might be the first time that VW 2.0TDI tech stagnates for a good few years after a noticeable but not revolutionary power increase - unless they finally get around to bringing a twin scroll turbo out.
You usually find with VAGs that between years 2 and 3, the monthly cost and monthly depreciation are almost equal.
I got a 2.0 TDI 140PD MK5 Golf on a 55 plate, kept it 2 years and then:-
I got a 2.0 TDI 170PD MK5 Golf on a 57 plate after my dad got one on 07 plate and it was massively better on performance. Once a bus clattered that at 2 weeks old and it took me another 7 weeks to get it back, it was never the same. It had a sh!te repair by Benfield and went back for lots of remedial work. The car was tainted and I resented it until…
The Scirocco 140CR GT came out and I got one on 09 plate. 2 months after I got it, the 170CR was announced and I wanted it.
Waited 2 years to get one on 11 plate because I’d have lost too much p/x-ing before that.
Scirocco 170CR was just under 2 years old when I ordered my GTD, knowing that the car would be 2 years old when I got my GTD.
A new gen Audi TT is the most likely cause of temptation coming out in the foreseeable.