Throughout the 1980s, touring car racing revolved around the highly popular Group A formula. This ruleset required a minimum production of at least 5000 examples for a car to be eligible for competition, and allowed very little outside modification.
As a result, the series became the epitome of "Win on Sunday, sell on Monday", as high-powered versions of ordinary cars took the war on the world's racetracks. With Volvo, Toyota, Alfa Romeo, Ford, Audi, Holden, Nissan, Maserati, Opel, Mercedes-Benz and BMW involved, chances were high you could see your personal grocery getter annihilate your neighbors family sedan.
Group A was a tremendous success.
Despite a highly successful run starting in 1982, by 1993 Group A disappeared. Four wheel drive monsters built by Audi and Nissan had crushed the opposition in Germany, Japan and Australia, a negative development compounded by a global economic recession.
As a result, the category was abandoned in favor of GT300/GT500 in Japan, an early version of the V8 Supercars in Australia, and FIA Class 1 and Class 2 in Europe. The high tech, incredibly liberal 2.5L Class 1 formula found a home in the DTM in the wake of the Audi debacle, while the 2.0L Class 2 took on the role Group A had enjoyed all over Europe.
Modeled after the 2 Litre Touring Car category introduced in the British Touring Car Championship in 1990, FIA Class 2 was Designed to put a stop to the tremendously expensive homologation process and increasingly complex designs seen in Group A. Ironically, despite this conservative attitude, the class would come to be known as "Super Touring".
Like in Group A, exterior modifications of the bodyshell were strictly forbidden, but contrary to the older formula the cars were restricted to two liter naturally aspirated engines of up to six cylinders, which had to be based on a production block, and were capped at 300 horsepower. Other than this, the manufacturers were free to choose a drivetrain of their liking.
BMW chose to reuse the engine from the original M3 for their entry into Class 2.
As with Group A, Class 2 quickly garnered support from a wide variety of big manufacturers, spurred on by marketing potential of racing the popular 2.0L engine size. Some of these brands like Toyota, Vauxhall/Opel, Nissan and BMW were able to get something of a head start, since they were already active in the BTCC.
BMW had entered a two door version of its new E36-generation 3-Series in 1992, badged as a 318iS despite the two liter engine. This was done out of sheer necessity, as the 320i was a six-cylinder car, and BMW wanted to use the ready-made S14 four cylinder engine from the E30 M3, instead of trying to convert the big, long and heavy six into a competitive race motor.
Joachim Winkelhock took the BTCC title in 1993.
With oldschool M3 power, the 318iS managed to take two titles in the BTCC, with Tim Harvey (GB) taking the 1992 championship, and Joachim Winkelhock (GER) reigning supreme a year later. Italy's Campionato Italiano Superturismo saw Roberto Ravaglia (ITA) secure top honors in 1993, while in Germany's Super Tourenwagen Cup Johnny Cecotto was victorious in 1994.
The final major championship wins for the 318iS came in 1995, when Yvan Muller (FRA) won the Championnat de France de Supertourisme, and Steve Soper (GB) grabbed the top spot in the Japanese Touring Car Championship.
The 318iS and 320i were quite successful on the European Super Touring circuit.
Aerodynamic aids had been introduced with Alfa Romeo's questionable 155 TS Silverstone in 1994, and became mandatory the following season, completely changing the face of the sport. By 1996, BMW had finally changed the name of their Super Touring challenger to reflect its actual displacement.
The updated 320i picked up right where its predecessor left off, winning the French title in 1996 and 1997 with Eric Cayrolle, and the Italian title with Emanuele Naspetti in 1997. While the car was still in its stride, BMW decided a publicity stunt was needed to promote a very different side of the market.
BMW was eager to promote their diesel offerings.
At the time, an increasingly bigger share of the European market was being taken up by diesel-powered cars. Due to their higher weight and initial high cost, diesel engines initially started to gain traction in larger vehicles in during the 1980s, but as the technology progressed, and diesels became less raucous, noisy and dirty, more and more brands starting offering an ever wider palette of oil-burning vehicles.
BMW had been somewhat late to the party, as their first diesel engine, the six-cylinder M21D24 was released in 1983 as part of the offerings for the E28 5-Series. Despite popular demand for smaller engines, a four cylinder variant didn't emerge until 1994, when the E36 318tds came to life bearing the 90-horsepower M41D17.
A Super Touring version of the 318tds was raced at the 1997 24 Hours of Spa.
In order to give the rattly engine some more sex appeal, BMW retrofitted a Super Touring chassis with a tds engine modified by Warthofer Racing, and entered it into the 1997 24 Hours of Spa under the BMW Testcenter Nurburg banner. Competing in the specially set up EcoTech category, the car faced off against diesel versions of the Renault Megane Coupe and the Volkswagen Golf.
The 318tds going head to head with the Volkswagen Motorsport Golf TDi.
Driven by veteran Peter Kox (NED), Emanuele Naspetti and Christian Menzel, the car qualified an impressive 7th overall. Helped by its vastly superior fuel economy, the car swiftly climbed up the order to finish just ahead of the Golf TDI of Jean-Francois Hemroulle (BEL), Raimund Baumschlager (AUT) and Jorg Seidel (GER).
In the process, the team clinched an amazing 3rd overall, 8 laps down on the winning factory BMW 320i driven by Didier de Radigues (BEL), Marc Duez (BEL) and 1993 Le Mans winner Eric Helary (FRA). Naturally, the team also snatched 1st in the EcoTech class.
BMW selected a pre-production example of the M47D20 to propel their ultimate diesel racer.
Not satisfied with merely grabbing a podium, BMW pressed on to improve on the concept for next season. As luck would have it, they were just finishing development of a new generation of diesel engines, the innovative common-rail injected M46D20 2.0L turbodiesel engine.
Though the new motor was actually intended for the coming E46-generation 3-Series, BMW thought it wise to show off a heavily modified pre-production example at the other popular 24 hour touring car race: the 24 Hours of the Nurburgring. With the E36 a ready made racing platform, the firm opted to repeat the trick seen at Spa. However, the car would named 320d instead of tds, reflecting the new nomenclature BMW would use for its successor.
In stock form, the M47D20 produced a respectable 136 horsepower and 280 Nm (207 lb ft) of torque. This was more than okay for a road car, but didn't measure up to the 300 horsepower figure normally seen in Super Touring. In order to close the gap a bit, the engine was reworked to push out 200 horsepower and 400 Nm (295 lb ft) of torque.
Seeing as this was still a far cry from the power available to top level Super Tourers, BMW's strategy was very clear. Instead of outright speed, the team would be banking on the car's enormous fuel economy advantage, similar to the effort at Spa the year before.
A modified six-speed sequential gearbox took car of power transfer to the rear wheels. Both steering and braking were left unassisted to both help offset the weight gained by fitting the turbodiesel, and to increase road feel for the drivers. Braking was handled by massive 345 mm discs in front and 280 mm examples at the rear, clamped down on by four-piston calipers. As with the petrol cars, 19 inch central locking BBS wheels were found on all four corners.
Given direction to longtime collaborator Schnitzer Motorsport, BMW prepared a two car assault on the famous 24 hour race. As it happened, the brand had a bit of a reputation to uphold, having won 15 out of 25 races since the event's inception in 1970. With this in mind, only the best drivers were selected to pilot the self-igniting superstars around the 25 kilometer circuit.
For #10, the team selected Christian Menzel, Le Mans veteran Marc Duez and Andreas Bovensiepen (GER), son of Burkhard Bovensiepen, the founder of famous BMW tuner Alpina. The sister car meanwhile enjoyed the talents of 1970 N24 winner and double Le Mans winner Hans Joachim Stuck (GER), 1995 JTCC champ Steve Soper and former MotoGP racer Didier de Radigues.
As had been expected, single lap qualifying pace was nothing to write home about. However, during practice Schnitzer Motorsport found the cars could complete dizzying distances on a full tank of fuel oil.
Because the diesel engine operated at far lower revolutions and relied on torque rather than top end power, the drivers had to drastically change their technique. The advantage of this phenomenon was the option to use far higher gears over the course of the lap, which helped save fuel even more.
Pitstop for the #10, Nurburgring 1998.
The tortoise versus hare strategy was proven to be right on race day. Despite an obvious speed difference, the cars could essentially stay out for as long as their tires lasted. In fact, the cars didn't need refueling until four hours of hard racing had passed.
Through sheer time-saving by staying out of the pits, the cars were creeping up on the faster competitors, including the factory petrol BMWs. After just six hours of running, the diesel 3-Series were running 1-2.
The car's almost magical endurance inevitably garnered unwanted interest from the stewards. One of the cars was summoned to come into to the pits as a result, in order to allow the officials to check its fuel flow meter. No evidence of glitches or foul play were found however, and the car was allowed to rejoin the race.
Five laps later, disaster struck for the leading #11 Stuck/Soper/De Radigues car. An incurable electrical fault unfortunately spelled the end for their race. Because of his star power and his Nurburgring expertise, HJ Stuck was added to the roster for #10, and the team went on their way.
Without any further issues, Stuck / Menzel / Duez / Bovensiepen sailed to a historic victory, covering 137 laps and 3343 kilometers (2077 miles) in 24 hours.. For the first time in motorsport history, a diesel-powered car had won a major endurance race. With this groundbreaking achievement, BMW had shown the world diesel cars were far more than rough-running, smelly smoking rattleboxes.
Just like the classic tale, the tortoise had beaten the hare. But with the reintroduction of GT cars at the N24 in 1999, and the eventual dissolution of Class 2 Super Touring in 2000 due to drastically bloated costs, the unique diesel Beemers would never race again.
Because of this, their performance at the 1998 N24 was seen as a fluke, until Audi confirmed the merits of using diesel in endurance racing once and for all with the dominant R10 TDI Le Mans prototype in 2006. As for touring cars, it would taken until 2007 for SEAT to introduce the a diesel version of the Leon under the World Touring Car Championship's D2000 rules.