After conquering the FIA GT Championship, Mercedes-Benz set its sights on competing at the 24 Hours of Le Mans in 1998, which it had not been at since 1991. However, Le Mans presented a different challenge from that offered in FIA GT, in that the race distances were nearly one tenth the distance covered at Le Mans. Therefore, Mercedes-AMG set about altering the CLK GTR in order to meet the new demands required at Le Mans.
First and foremost, Mercedes-AMG decided that the M120 V12 would not be up to the task of running for 24 hours. Instead, they decided to use the M119 HL V8 engine from Sauber C9/Sauber C11 which raced in the late 1980s and early 1990s, as Mercedes-AMG felt that the M119HL would have better reliability at speeds while still performing the same amount of power as the M120 due to air restrictor regulations. The turbochargers were removed and other revised components were added in order to achieve high rpm. The modified engine was designated as GT108 B.
Satisfied with the engine, Mercedes-AMG also set about altering the bodywork to better cope with the high speeds of Le Mans. The nose was lowered and the large front brake cooling ducts on the sides of the nose were removed and replaced by a single, large opening in the front of the car. The roof of the car was also lowered and a new engine air intake was designed for better engine cooling along with various other mechanical tweaks. This new car would become known as CLK LM, with the LM designation standing for Le Mans.
Debuting at the 1998 season of Le Mans, the twin CLK LMs entered were immediately quick. The two car team took the pole, ahead of custom built open cockpit Le Mans prototypes. However, Mercedes-AMG's belief of the M119LH engine's reliability and capability was proven wrong as both cars suffered engine failures within the first few hours of the race, leaving Mercedes-Benz dejected.
Returning to FIA GT, Mercedes-Benz replaced their older CLK GTRs with the new CLK LMs and saw greater success. The two cars easily won every remaining race, including six 1-2 finishes. This handed Mercedes-Benz the teams championship again, while Klaus Ludwig and Ricardo Zonta would share the drivers championship.
For the 1999 season, no competitor attempted to enter the GT1 class in FIA GT except for Mercedes-Benz, forcing FIA to cancel the class, similar to the DTM/ITC two years earlier. Mercedes-Benz thus turned to constructing an all-new car to overcome their failure at Le Mans. No longer forced to build a racing car that could also be a road car, Mercedes-AMG set about creating the Mercedes-Benz CLR.
The CLK LM's V8 engine produced approximately 600 hp (608 PS; 447 kW), allowing it to reach speeds up to 330 km/h (205 mph) in testing for the 1998 24 Hours of Le Mans disregarding a claimed virtual top speed of 335 km/h (208 mph). In total, four CLK-LMs were constructed, with two road-going versions built to comply with the 1998 FIA regulations.