I know the A7 class quite well and i would prefer the Mercedes Benz CLS class over it. It looks better, the back seats are more comfortable and they fit better with tall people. And you can get it with a 5.5 litre Biturbo V8 that really kicks your ass (it accelerates the CLS faster then a Porsche Turbo, with a weight of nearly 2 tons.
And if you pimp it, you can go as fast as the best Porsche ever built (Carrera GT), like 350 km/h (for the non-metric systemers: 220mph).
All possible on german autobahn.