I've just had myself a 2007 2.0TFSI Quattro from an Audi Dealer (so one year warranty e.t.c) and my girlfriend has noted it's quite sluggish. We then proceeded to have a little race between mine and her A3 2.0tdi 140, and i hardly made any ground over about 600m, from starting at about 20mph. The car has recently just had a new Turbo control unit, due to a solenoid valve making clicking noises. I've been searching both here and the web and haven't come up with any definitive answers as to what could be causing this. I have seen many suggestions however. These include
1. Carbon buildup in the intake manifold
2. Spark plugs
3. The fact it's just been filled up with regular unleaded from a supermarket forecourt (dare i say that here?)
I was wondering if anyone has experienced anything similar? Or has any idea of which cause, if any of the above, it is likely to be?!