Audi has just proved that there really is safety in numbers by producing its five millionth quattro all-wheel-drive-equipped model – an A6 allroad. The rugged, air-suspended Avant is just one of over 140 variants across the Audi range currently benefiting from this invaluable all-weather grip enhancer, which made the pioneering transition from rally stage to road courtesy of the Vorsprung durch Technik brand back in the Eighties.

“quattro is one of the key pillars of our brand and has been a critical factor in our successful history,” said Rupert Stadler, Chairman of the Board of Management of AUDI AG. “The quattro permanent all-wheel drive system makes it possible to directly experience our ‘Vorsprung durch Technik.’ We are committed to our pioneering role and will continue to develop this advantage with new technologies.”

An instant hit at the 1980 Geneva Motor Show, the 200PS Audi quattro showcased the first mainstream four-wheel-drive system. It triggered the intensive development that has culminated in today’s leading edge Audi all-wheel-drive technology, which instils impressive all-weather traction and exceptionally high limits of adhesion in the latest quattro variants.

Last year, more than 43 per cent of Audi customers opted for the added reassurance of quattro, and the Neckarsulm plant in Germany – home of quattro GmbH – equipped one car in every two on the production line with the technology.

Audi quattro: the latest incarnation

A rear axle-mounted multi-plate clutch version of the quattro system currently safely contains Audi models with transversely mounted engines from the Q3 through to the TT, and a further developed version will soon return to the all-new A3 and 300PS S3. Models with longitudinally mounted engines, including the A4, A5, A6, A7, A8 and Q7, divide their torque across all four wheels by way of a self-locking centre differential, the most advanced version of which is the crown gear differential used by RS 4 Avant, RS 5 Coupe and RS 5 Cabriolet models, and soon to feature in the forthcoming RS 6 Avant and RS 7 Sportback models.

The advanced crown gear differential channels power to where it is needed, and away from where it isn’t, more quickly than ever before in the interest of optimal handling composure and agility. Up to 70 per cent of torque can be apportioned to the front axle, and up to 85 per cent channeled to the rear, where in the RS models a sports differential is also on hand to divide power between the rear wheels in the most effective proportions possible.

The latest generation R8 incorporates another variation – a viscous coupling capable of diverting between 15 and 30 per cent of torque to the front wheels, depending on conditions. Located on the front axle, the coupling is powered through a cardan shaft that runs to the front from the transmission through the engine’s crankcase.

Motorsport domination

Since its humble beginnings in 1981, quattro all-wheel drive has monopolised motorsport with formidable performances on track and tarmac. Four titles in the rally world championships (Driver’s & Manufacturers’), three overall victories at Pikes Peak, a championship win in the TransAm (Driver’s & Manufacturers’), two DTM titles, almost 20 national touring car championships (Driver’s & Manufacturers’) and the FIA Touring Car World Cup have been notched up by Audi thanks in no small part to the supreme control and grip supplied by quattro.

Audi quattro in detail – the road to success

The origins of quattro can be traced back to the winter of 1976-77, when a group of Audi engineers conducted test drives in the deep snow in Sweden. A Volkswagen Iltis was also participating for comparison purposes, and despite its mere 75PS output, the leggy all-terrain vehicle easily outran the much more powerful Audi prototypes with their front-wheel drive systems. A few weeks later a small team of engineers led by Dr. Ferdinand Piëch, then the Audi Board Member for Technical Development, began developing an all-wheel-drive car.

Their tour de force, which made the possibility of series production genuinely viable, was a seemingly simple hollow shaft, the integration of which permitted construction of an all-wheel drive system that was virtually tension-free, light, compact and efficient, and that operated without the need for a heavy transfer case or second cardan shaft.

The hollow shaft was a drilled-out secondary shaft in the transmission through which power flowed in two directions. It drove the centre differential from its rearmost end. The other half of drive torque was transferred to the front axle’s differential along an output shaft rotating inside the hollow secondary shaft.

The revolutionary technology made its world debut at Geneva in 1980 in the new Audi quattro, a 200PS sports coupé which was originally destined for production in low volumes. Such was the demand for this now legendary four-wheel-drive crusader, though, that it remained in the model line-up right up until 1991. In 1984 the compact, short wheelbase Sport quattro with 306PS was also added, and in 1986 the first generation model’s manual-locking centre differential was replaced with the Torsen differential (Torsen = torque sensing). This worm gear transmission was capable of variable distribution of drive torque. The next big step came in 2005 with the planetary drive that offered asymmetrical, dynamic distribution of the power.

In parallel, Audi further expanded its line-up of quattro models, and early on in the 1980s elected to offer the system in every model line; the new models were important milestones on Audi’s path to the premium segment in the market. The first TDI with permanent all-wheel-drive appeared in 1993; four years later the technology moved into the compact segment.

Audi quattro – the motorsport connection
In early 1981 the quattro was launched headlong into the world championship scene, and quickly dominated it. Hannu Mikkola of Finland won the first six special stages in the snow on the Monte Carlo Rally, but unfortunately, despite a lead of almost six minutes, had to concede defeat after his car made contact with a wall. By as early as 1982, the quattro had proved itself unbeatable; Audi redefined the benchmark with seven victories and captured the Manufacturers’ Championship. The following year Mikkola took home the drivers’ title.

The 1984 season also started off with a bang – the newly recruited two-time world champion Walter Röhrl won the Monte Carlo Rally ahead of his team colleagues Stig Blomqvist (Sweden) and Hannu Mikkola. At the end of the season, Audi took the world Manufacturers’ title as in 1982 and Blomqvist won the drivers’ title.

The final car was the Sport quattro S1. It celebrated its greatest triumph in 1987: Walter Röhrl stormed up the 156 curves of Pikes Peak in Colorado, USA, in absolute record time with about 600PS of power at his disposal.

In the following years, Audi shifted its focus to racing touring cars. Starting in 1988 the brand raced in the TransAm series and won the title on its first attempt. In 1990 the brand switched to the German Touring Car Championship, or DTM, and Hans Stuck also took the title here in the first year with the large and powerful V8 quattro.

Audi became the first manufacturer in the history of the German Touring Car Championship to stage a successful defence of its title.  Frank Biela rounded off an impressive first season for Audi with a double win in the last race of the season at Hockenheim, succeeding his team-mate Hans-Joachim Stuck – placed third – as champion. In 1996 the A4 quattro Supertouring, with its two-litre, four-cylinder engine, entered seven national championships on three continents – and won them all.

Two years later the European ruling bodies banned all-wheel drive almost completely from touring car races. The Audi balance sheet up to that point read as follows: four titles in the rally world championships, three victories at Pikes Peak, a championship win in the TransAm, two DTM titles, eleven national touring car championships and a touring car world championship. All-wheel-drive didn’t reappear again in racing until 2012. The hybrid-diesel Audi R18 e-tron quattro interpreted the formula in a new and groundbreaking way – and immediately celebrated a dazzling one-two victory in the Le Mans 24 Hours.