What's your call: Audi RS 8 5.2 Quattro vs. Mercedes SLS AMG Gullwing

You make the call. This:

2010 Audi R8 5.2 FSI Quattro: "...giving the R8 more power — about the only area where the car could be considered lacking — was literally as easy as dropping in the direct-injected 5.2-liter V-10 from the Lamborghini Gallardo LP560-4, that 552-bhp powerplant a descendant of the FSI V-10s Audi designed for the S6 and S8 sports sedans in late 2006. The main differences between the Gallardo and R8 engines lie in engine mapping and intake and exhaust tuning, which result in 525 bhp (DIN) and 391 lb.-ft. of torque, making the R8 5.2 the most powerful Audi production car ever..."

...Or this:

Mercedes-Benz SLS AMG Gullwing: "Under the SLS AMG's long hood is a version of the V-8 that we've seen powering every Merc of this generation with an AMG badge--although, this time the engine actually displaces 6.3-liters. Output has been tuned to 563 horsepower and 479 pound-feet of torque..."

Well? Watcha think?

Idea: Autospies.