At least the four years of finance (so that's another 29 months). Will probably then save for another year the amount I pay for the GTi to give me a deposit on top of the value of the car - so at least 5 years.
At that point, I have to decide to buy something else (and at probably nearly £30k by then) that'll most likely be a fast BMW. Much as I love this car it's just a VW and the one I have is just about the limit for me in terms of price.
I could get a used M3 for £30k as an example.