Hi, the A3 is basically a Golf in drag. I haven't checked lately but I'd think that the Audi would command a premium. The quattro will probably be about the same in performance as the Fwd cars, even though the car you mentioned has 30bhp more. Go and drive some, you're not going to buy a car on someone elses say are you?
Both of the 150bhp cars can be mapped to about 210bhp (The drive by wire cars are more susceptable to tuning)
Best advice is to drive one. Best of luck
