I actually prefer the turbo-diesels for their tremendous low end torque - makes the car feels very muscular. They only lose out to the petrol driven engines at high (read >100mph) speed overtaking on highways, but will still score on frugal consumption. But that is personal, I guess. Heee... and you have to bear with the slightly rougher engine sound.
I just got an Audi A8 4.2TDI from Sixt. Nice car, great torque, and very fuel efficient.