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The distinctive warble of Audi's five-cylinder powerplants must be one of the most iconic sounds in the automotive world. The concept is celebrating its 40th birthday this year, so it's a good opportunity to take a peek through its eventful history.
The first appearance of a five-banger was in the Audi 100 in 1976. It was adopted from the EA827 four-cylinder unit, and its development came about due to concerns that a six-cylinder would be too big and cumbersome, especially as the longitudinal placement under the bonnet meant that a large amount of weight hung out past the front axle. New-fangled fuel injection meant it produced 134hp from its 2.1 litres, with a turbocharged version pushing out close to 170hp. Those who preferred the devil's fuel and felt no particular need to go anywhere in a hurry could specify a naturally-aspirated 2.0-litre diesel, which kicked out an earth shattering 69hp.
Audi had also started to experiment with all-wheel drive vehicles around this time. At the forefront of this was the Ur-quattro, which saw the addition of intercooling boost power in the road car version to 200hp. On the rally stages, it was a different story altogether. The bespoke aluminium unit on the homologation-special Sport Quattro saw 300hp breached for the first time, but in full competition trim it was more like 450hp. The pace of development of Group B rallying at the time saw a power war like nothing before or since, with special fuels and copious amounts of boost culminating in an engine which had the potential to produce almost 1,000hp. This was tried out on a pre-rally test, but not even the legendary Walter Rohrl could tame it, pronouncing it as ''completely undriveable''. The Pikes Peak hillclimb and IMSA GTO series both saw success for the German marque in addition to multiple rally wins and championships, all powered by the five-cylinder unit.
Towards the end of the Eighties, the diesel gained direct injection, a turbo and electronic control to drag 120hp out of its 2.5-litres. Of more interest to enthusiasts was the crazy RS2 Avant. With input from Porsche, 310hp and all-wheel drive, it set the template for every uber-estate to this day, and is highly sought after nowadays. By 1997 however, the five-cylinder had been phased out, and you'll need to find an S6 from that era if you want your own piece of the original heritage.
Come 2009, Ingolstadt decided to reintroduce a five-cylinder engine to its range, offered exclusively in the high performance RS models. Evolution from 335hp to almost 400hp in the latest TT RS puts it on a par with the Group B monsters of old, except in a much more efficient and environmentally-friendly manner. The sound is still the main attraction however, and if you haven't experienced it first hand, you're missing out. This 2.5-litre powerplant has won ''Engine of the Year'' in its category every year since 2010, so the international motoring press obviously hasn't tired of being serenaded by it just yet.