In 1996 Mercedes-Benz’s motorsports programmes included support for cars in Formula One, IndyCar, and the International Touring Car Championship (ITC). Following the collapse of the ITC at the end of the 1996 season, Mercedes’ attention shifted to the FIA GT Championship. Racing partners AMG were tasked with developing a design to meet the Fédération Internationale de l'Automobile's GT1 regulations for the new championship. The new cars, known as CLK GTRs, were designed for use both as racing and road cars, as series regulations required the racing cars to be based on production models. The CLK GTRs were successful in their debut season, winning seven of eleven races and earning both the drivers’ and teams’ championships.
For the 1998 season AMG refined the CLK GTR’s design with the launch of the new CLK LM. A major change was the replacement of the CLK GTR’s V12 engine with a smaller V8, thought by Mercedes to be more suitable to take on longer endurance events such as the 24 Hours of Le Mans. Despite earning pole position for Le Mans, the new cars were unreliable and both lasted less than three hours before retiring with mechanical failure. The race was won by Mercedes’ FIA GT rivals Porsche. Mercedes did go on to win its second straight FIA GT Championships later that year after winning all ten races.
After the dominance of Mercedes, most of the GT1 class competitors chose not to return to the FIA GT Championship for 1999, leading the FIA to eliminate the category from the series. The Automobile Club de l'Ouest (ACO), organisers of the 24 Hours of Le Mans, chose to follow the FIA’s lead and no longer allow GT1 category cars to enter Le Mans. While FIA GT concentrated solely on its lower GT2 category in 1999, the ACO created a new category of race car known as a Le Mans Grand Touring Prototype (LMGTP). Mercedes, no longer able to compete in the FIA GT Championship with the CLK LMs, chose to concentrate on the ACO’s new LMGTP category.
Work on designing a new car to meet LMGTP regulations began in September 1998 as Mercedes was closing out its second FIA GT Championship season. Development was led by HWA GmbH, which became an independent company the following year. The LMGTP rules did not require road versions of the cars to be built, allowing chief designer Gerhard Ungar to develop the CLR without concern for road legality issues. The transition from GT1 to LMGTP also allowed a decrease in the minimum allowed weight, from 950 kg (2,090 lb) to 900 kg (2,000 lb). The new design had a much smaller cockpit monocoque made from carbon fibre and aluminium honeycomb. The monocoque design derived its lower half from the CLK LM’s combination of carbon fibre and steel tube frame, but required a full carbon and aluminium upper half due to new load tests. The bodywork of the CLR was 10 cm (4 in) shorter in overall height compared to the CLK LM, while the nose was substantially lower and flatter due to a shorter wheelbase allowing longer overhangs. Aerodynamic development was carried out at the University of Stuttgart’s wind tunnel and assisted by the aerodynamic specialists Fondmetal Technologies, with emphasis placed on low drag for maximum top speed. Mercedes-Benz’s brand image was retained with the reuse of CLK-Class styled tail lights from the CLK LM and a front fascia, grille and headlamps based on the then-new CL-Class.
The engine for the CLR was a variant of the design used on the CLK LM. The GT108C 32-valve naturally aspirated V8 engine was loosely based on the M119 engine used in Mercedes-Benz road cars at that time. A previous variant of the M119 had won Le Mans for Mercedes in 1989. Displacement was increased from 5.0 L (310 cu in) to 5.7 L (350 cu in) to compensate for the new air restrictor limitations, allowing the engine to produce approximately 600 bhp (450 kW; 610 PS). The Xtrac 6-speed sequential gearbox came directly from the CLK LM, while Bridgestone continued as the team’s tyre supplier. The suspension setup from the CLK LM was largely carried over to the CLR, although a central spring was added to the rear suspension.
Mercedes publicly announced its CLR programme in February 1999, after testing at California Speedway and Homestead-Miami Speedway. Further testing continued at Circuit de Nevers Magny-Cours, where three CLRs completed a 30-hour test session covering 8,073 mi (12,992 km). On 20 April, the CLR was shown to the press at the Hockenheimring, having covered 21,735 mi (34,979 km) in testing without major failures.
The initial schedule for the CLRs consisted of participation in the May pre-qualifying and testing session at Le Mans. Plans were announced to enter several races after Le Mans, including an exhibition event at the Norisring, and the final three races of the American Le Mans Series. More than 200 personnel from Mercedes-Benz and HWA formed the crew for the three cars, operating as AMG-Mercedes.
Mercedes named nine drivers to the team: Christophe Bouchut, Jean-Marc Gounon, Bernd Schneider, Marcel Tiemann, and Mark Webber, retained from the FIA GT programme, along with Nick Heidfeld, Peter Dumbreck, Pedro Lamy, and Franck Lagorce. Darren Turner served as the team’s reserve driver for Le Mans.
Mercedes received a single guaranteed entry for Le Mans due to their 1998 FIA GT Championship win, assigned to Gounon, Tiemann, and Webber in CLR No. 4. Bouchut, Dumbreck, and Heidfeld in No. 5, and Lagorce, Lamy, and Schneider in No. 6, had to pre-qualify. The No. 6 car was the sixth fastest, while Nos. 4 and 5 were 14th and 15th respectively, successfully passing pre-qualifying.
During the qualifying sessions, Webber crashed CLR No. 4, becoming airborne and impacting the barriers. He was taken to a hospital suffering from a sore neck, chest, and back. The car was rebuilt using a spare monocoque. Despite the accident, Schneider secured fourth place on the grid for No. 6 with a lap time of 3:31.541, while Toyota took pole position.
On the morning of the race, Webber crashed CLR No. 4 again during the warm-up session, becoming airborne and landing on its roof. Mercedes withdrew the damaged CLR but chose to continue with the remaining cars, instructing drivers to avoid closely following each other.
With only two CLRs remaining, Mercedes started from fourth and seventh on the grid. Nearly four hours into the race, Peter Dumbreck in CLR No. 5 became airborne, vaulting the safety barriers and crashing into trees. Mercedes immediately withdrew the remaining car from the event and cancelled the entire CLR programme.
The ACO and FFSA investigated the incidents. The ACO cited the CLR’s design as a contributing factor and changed the regulations for the LMGTP category in 2000, decreasing the allowable length of overhang. The FIA also instructed its Advisory Expert Group to develop new regulations to prevent similar airborne accidents. The LMGTP class was abandoned by the teams in 2000, reappearing in 2001.
Mercedes-Benz cancelled the rest of its 1999 programme, withdrawing from the Norisring exhibition event and the American Le Mans Series. The company returned to touring car racing in 2000 and did not participate in Le Mans again until 2024, with customer GT3 entries.
Despite the failures, Christophe Bouchut considered the CLR his favourite car to drive at Le Mans. The remaining car has since appeared at events and is now on display at the Nationales Automuseum in Germany. The accidents have become infamous in motorsport history.