Audi's current racing activity has evolved a long way from its heritage, but the spirit of the past lives on in its production cars--or at least in the TT RS's five-cylinder engine, which traces its origins back to the Audi 90 Quattro.

That car won fame in the IMSA GTO class, driven by racing legend Hans-Joachim Stuck. Stuck remembers the engine fondly, remarking on its compact design and its instant power delivery.

Whether you're an Audi fan or not, you have to recognize the brilliance of the powertrain--especially as applied in the new TT RS, which you can read more about in our first drive review, where Bengt Halvorson calls the power made by the 2.5-liter turbo five "extremely addictive,"  delivering a "strong[er] kick than the V-8 powertrain in the last Audi RS4."

Audi is living up its historic ties to motorsport through its current lineup this week, having teased us with a shot of an RS5 that appears to be headed to Pikes Peak earlier today.