Launched at 2007's Frankfurt Motor Show and available from mid-2008, the current-model Audi RS6 Avant (or, to give it its full and proper name, the Audi RS6 5.0 TFSI quattro Avant) demonstrates perfectly how, while the quattro system has adapted brilliantly to incorporate the most cutting-edge modern technology, the fundamental principles remain as solid as when the system was first invented.
As of January this year, the RS6 is the most powerful car ever produced by Audi - easily beating out its competitors, the BMW M5 and AMG Mercedes E63 with a zero-60 time of 4.6 seconds and an electronically limited top speed of 155mph which can optionally be de-restricted, giving the car a 170mph top speed.
Launched in 2006, the R8 is Audi's first supercar - and as well as being equipped with quattro, it's also actually made by quattro - quattro GmbH, that is!
quattro GmbH is the name of Audi's high performance subsidiary company, formed in October 1983. And yes, like the four-wheel-drive system we're here to celebrate, it's spelt with a small "q". The company is HQ'd in a 3500 square metre site at Necarsulm, within the former site of NSU (which became part of the Audi group in 1969). The company produces the Audi RS4, Audi RS6 and the R8, as well as quattro-branded high-end merchandise and accessories.
One of the most unusual - and successful - applications of the quattro system was in 1989's IMSA Audi 90 quattro GTO.
After the Group B category was dropped from the World Rally Championship in 1986, Audi took the Sport Quattro to success on the Pike's Peak hillclimb. But after winning three times, they decided to try the Quattro system at something new - the International Motor Sports Association (IMSA) Trans Am Series in the US.
The Sport Quattro was created to allow Audi to compete against the Lancia 037 and Peugeot 205 T16 in the World Rally Championship's Group B.
Introduced by the FIA in 1982, Group B let makers take huge advantage of available technology because it required that just 200 cars be produced to homologate a vehicle, and had no restrictions on turbocharging. As a result, 1980's Group B cars were some of the most powerful in the history of rallying - and some of the furthest-removed from their production equivalents.
It's hard to believe, but Audi's quattro system is 30 years old this year.
Previous attempts had been made at taming four-wheel-drive to the extent that it could be used to enhance sporty road cars, but none had fully succeeded in the way Quattro has. Development of the system started in 1977, when Audi engineer Jörg Bensinger realised that the Volkswagen Iltis, a four-wheel-drive military jeep-typevehicle, could out-handle pretty much any other vehicle in the snow. Starting with a red, two-door Audi 80 mule, Bensinger began testing how the Iltis' four-wheel-drive system would work in a car designed for performance.