They pushed back the diesel option. The new R8 is a 5.2 liter version of the Gallardo's V10. It's about 525 HP. It's already out in Europe:
http://www.audi.de/de/brand/de....html
And no, you can't compare a "budget" sports car, like the Z with a supercar like the R8. It may not be "much faster" but it's a whole other world. From the magnetic dampers, to the mid-mounted quattro engine, to the fact that the leather option is way over $10.000 (7.900 euros), the "carbon" option is another 8,600 euros ($13.000) and so on. A luxury car is just that, "luxury".
I love my Z, but I live in the real world, I know how deep my pockets are and I won't try to compare a budget-built performance car to an all-out german offensive of automotive engineering. Audi were out to beat Porsche (911) with the R8, not the Z.
P.S. Why not compare the Z with the 911? See? That's the GT-R's job.