This is footage of German rally legend, Walter Rohrl, driving the monstrous Audi S1 at some kind of historic rally event. The S1 was introduced in 1985 as an update to the original Audi Quattro rally car. It has a 2.1 liter turbo inline 5 that produces over 500 horsepower at 8,000 rpm. The engine produces a very unique exhaust note with some definite similarities to a high revving V10.