Among the RS4's key ingredients: A normally aspirated, 8250-rpm, 420-hp V-8 that shares only water and steering pumps with the S4's V-8.
There's no sense in holding out. The truth is so important, it needs to see daylight right here and now: The 2006 RS4 is the purest driver's car from Audi in the past two decades. Although Audis have always been sporty machines, the company's reputation for harder-edged performance dates back to the 1982-86 Coupe Quattro. That car used the first iteration of Audi's Quattro all-wheel-drive system and housed a 160-hp turbo five-cylinder under its long hood. The flared-fender coupe was underpowered and expensive ($35,000) in U.S. trim, but it was nothing short of iconic. It was astonishingly easy to drive fast in the dry, and its wet-road grip bordered on the sublime. Between 1982 and 1984, Audi Quattros effectively dominated the World Rally Championship. They also single-handedly ended the two-wheel-drive rally-car era.
Photo Gallery: 2007 Audi RS4 - Car Review & Road Test - Automobile Magazine