After Audi completely revolutionized rally cars by introducing their Quattro car with all wheel drive they started to see that they could improve on their design. The original car was too long and didnt rotate quickly enough for tight rally courses. Just like the other manufacturers, Audi used the lenient homologation requirements to create a new rally car. All they needed for homologation was a production run of just 200 cars. There was a distinct difference though in Audi's approach as the Roland Gumpert led engineers used the existing 'urQuattro' design as a basis. The likes of Peugeot and Lancia went one step further by developing their Group B racers from the ground up around custom-built spaceframe chassis.
One of the original Quattro's biggest problems was addressed by shortening the wheelbase. A section of 320 mm (12.6 inches) was cut from the chassis behind the doors. With the engine still mounted ahead of the front axle, the short wheelbase Sport Quattro had massive overhangs that made for very strange proportions. Further weight was cut by replacing most of the steel body panels with lightweight composites like Kevlar and fiberglass and aluminium.
The all-aluminium five cylinder in-line engine was also a development of the existing design. It displaced just over 2.1 liter to slot into the three-liter class (for turbocharged engines a 1.4 equivalency factor was used). In competition trim, the turbocharged engine produced at least 350 bhp. As mentioned earlier the entire engine was mounted ahead of the front axle. Although this was not the most obvious location for the engine, it make installing the Quattro all-wheel drive system considerably easier.
Priced at a staggering 203,850 German Marks, the 300 bhp homologation special was introduced during 1983. By May 1st of 1984 the required 200 cars were constructed and the Sport Quattro was fully homologated. Audi's new rally weapon was handed to an all-star driver line-up that included Hannu Mikkola, Walter Röhrl, Michele Mouton and Stig Blomqvist. Considering that the previous Quattro had still been good enough to help Mikkola win the 1983 World Rally Championship, expectations for the new Sport Quattro were understandably high.
Blomqvist's spectacular, very sideways driving style suited the Sport Quattro perfectly. By flicking the tail out, the Swede overcame the natural understeer of the nose-heavy Audi. He won five of the twelve rounds and was crowned the 1984 World Champion. Mikkola and Röhrl also won a round, which was enough to clinch the constructor's trophy as well. The writing for the Sport Quattro was on the wall; the mid-engined Peugeot 205 T16 introduced halfway through the season had won three of the last four rallies of the year.
The Group B regulations allowed for an evolution an existing car under the condition that an additional 20 examples were produced. This allowed Audi to create the Sport Quattro S1, which was introduced at the 1000 Lakes rally in August of 1985. Visibly it was quite a dramatic make-over thanks to a massive scoop on the nose and a large rear wing. The awkward weight balance was also addressed by moving the radiators, battery and other auxiliaries to the rear of the car.
Further modifications under the the kevlar body panels concentrated on the drivetrain. The turbocharged 'five' now produced well over 500 bhp, which came at the expense of low-end grunt due to the turbo-lag. To counter that the S1 was fitted with an anti-lag system that fed fuel into the turbo to keep it spinning even when the throttle was closed. The resulting bangs and exhaust-flames were immediate fan favourites. At some rallies, Audi also experimented with a 'PDK' dual clutch automatic gearbox.
By the time the Sport Quattro S1 made its debut, the Peugeot 205 T16 had already won six rallies out of a possible eight. At the new car's first outing, reigning champion Blomqvist scored a commendable second with the S1, behind a Peugeot of course. Röhrl salvaged the season for Audi by winning the San Remo Rally. There the massive power and traction of the Audi gave it the edge over the better handling and much nimbler Peugeot. Having barely caught on with the Peugeot, Audi was confronted with an all new turbocharged and supercharged Lancia at the final round of the season.
Audi's engineers worked hard over the winter on the engine, which reportedly produced in excess of 600 bhp at the start of the 1986 season. The podium of the traditional season opening Rallye Monte Carlo was telling with a Lancia and Peugeot heading the third placed Audi of Mikkola. Audi's presence in the World Championship came to a dramatic end after the Rallye de Portugal. Three spectators were killed and a further 30 were injured after a Ford RS200 pilot plunged into the crowd. Audi announced their withdrawal from the sport shortly after.
Audi also dispatched the Sport Quattro and Sport Quattro S1 to the United States for the annual Pikes Peak Hillclimb. In 1984 Michelle Mouton became the first woman to win 'The Race to the Clouds.' In 1985 she repeated that feat in a Sport Quattro S1. Bobby Unser continued Audi's winning streak in 1986. With Group B cancelled in 1987 the competition at Pikes Peak was much stronger that year. Röhrl was handed a mildly modified Sport Quattro S1 with an even wilder bodykit. The turbo boost was raised to produce a rumored 1000+ bhp. The German rally-legend won at his first attempt.
Audi's world rally program lasted less than five years but its influence can still be felt. With four championships, the adventure was also highly successful for Audi. The Sport Quattro and the extreme Sport Quattro S1 represented the final development of the 'urQuattro' and remain as the most powerful rally cars ever built. The valuable lessons learned were later applied to GT and Touring car racing, winning Trans-Am, DTM and BTCC titles in the following years.
In both TRans Am and BTCC the Audi cars were banned for having too much of an advantage with their Quattro systems over all the other cars. But thats a story for another time...
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