I have had my 2.0T for 2 years in August, i bought it with 48k miles on, it now has 79k miles, that's 31k miles in 2 years, i probably stick on average about £40-50 a week in the tank, i normally just fill it up at about £60/£65, and that tank will last about 9-10 days, both work out about the same. Like i say, i don't drive like a granny, at the same time, i don't drive foot to the floor all the time either, i sit at about 80/85 on the M/way and my driving varies between A roads and town roads (30mph).
I can't compare to my old mondeo (TDCi 130) where petrol vs diesel is concerned, but i don't think i'm spending that much more than i was then, other than the obvious increase in fuel costs in 2 years. Yes, there probably will be a difference, infact, more definite a difference lol, but i just can't say it's been that obvious to me, i fill it up, and drive it. All i will say is that i thought it would use more fuel than it does for a 2.0T 200ps engine with decent performance.
In 2 years, i have a had a couple of problems though, firstly, one coil pack and he wiring loom needed replacing as it had burned at the coil pack connector

this was fixed under warranty thankfully, also, a sensor attached to the turbo caused a fault with my DSG box, this would make it stick in gear occasionally, could be 1st or 3rd gear. Again, this was fixed under warranty, now i need to replace a ABS sensor too.
Overall, i've been very pleased with my car, however, i wouldn't spend £17k on one, i'd be looking at an A4 cab for this money (personal preference and not the choice of many other people i would imagine - i just love them).