The BMW M6 has got some hefty competition coming its way. Checkout these recently released amazing spy photos of a prototype Audi RS5 undergoing testing at the Nurburgring. While the Audi S5 really just an Audi A5 on steroids, the RS5 is the S5 on steroids. The RS5 will debut at the Frankfurt Auto Show in September this year. We are pretty sure though that it will go on sale in 2010 in Europe. Stay tuned to Carzi for regular updates. We know that you will.