I've traveled to Spain for the AMG press event. I've driven the cars. I've talked to the public relations people, the marketing folks, the engine guru they hired back from Porsche, and a member of the board. After all of that, I still don't understand why AMG and Mercedes-Benz have designed a bespoke 6.2-liter V8 engine, which they are calling a 6.3L, that commemorates an AMG racing victory in 1971 with a 6.3-liter V8 engine that was actually a 6.8L. Confused? I'll try to explain.
In the beginningAMG has been around for nearly 40 years. It was started in 1967 in an old sawmill in Grossaspach, Germany, by Hans Werner Aufrecht and Eberhard Melcher. The fledgling company took its name from the A and M of the founders' last names and the G from the town where they were located. AMG's purpose was simply to tune Mercedes-Benz models to higher performance levels. Mercedes-Benz had contested a few international rallies during the 1960s, but hadn't been a real force in racing since the heyday of the 300SL sports car almost a decade earlier. There were no other tuners specializing in Mercedes-Benz at that time, yet the choice was an obvious one for the two former Mercedes-Benz engineers who started the company. They also knew that there was a new Mercedes model on the horizon that promised to put both AMG and Mercedes-Benz squarely in the performance game.
300SEL 6.3In 1965, Mercedes-Benz replaced its "fin-back" sedans with the W108 and W109 series "square-backs." These roomy and comfy six-cylinder four-door sedans had good performance, especially the six-cylinder 300SEL model with its 185 bhp. There was more coming. Mercedes-Benz engineer and racing fanatic Erich Waxenberger and Mercedes Racing Chief Rudolf Uhlenhaut looked at the huge 6.3-liter V8 from the 600 Pullman Limousine and realized that it would just fit in the 300SEL's body shell. The 6.3L had a cast-iron block and aluminum heads with single overhead camshafts. With 6,329cc, the V8 made 300 bhp and 434 lb-ft of torque. The resulting two-ton 300SEL 6.3 would accelerate from zero to 60 mph in 7 seconds and could hit an aerodynamically limited 137 mph. With a stock limited-slip rear axle (very necessary) and four-wheel disc brakes (even more necessary), reviewers quickly ran out of superlatives with which to describe the car. Racer/engineer Waxenberger brought one to Macao off the coast of China and won a six-hour touring car race in 1968. With approval from the company, the charismatic engineer prepared three cars for the 24-hour race for touring cars that would take place at Spa in Belgium in July 1969. This was the first "official" race participation of the German company in 15 years. The cars were fast in practice, but the tires couldn't hold up to the high speeds of the heavy sedans and the cars were withdrawn before the start of the race. Waxenberger continued his development of the big machines, fitting larger wheels and tires, fender flares, and boring the engine out to raise its capacity to 6,834cc.
Enter the guys from GrossaspachWith a looming energy crisis and uncertainty in the Daimler-Benz boardroom, racing was curbed in the early 1970s. It had to be frustrating for Waxenberger and his crew of racers to know that they had a potent racing machine in the big-engine sedan. What happened next was inevitable: Under-the-table equipment and know-how created by Waxenberger's team showed up at AMG's sawmill to help out some fellow racers. Hans Aufrecht bought a wrecked 300 from a local doctor and set about building a racecar. They built up a 6.8-liter V8 engine that made a reliable 398 bhp at 5600 rpm and went to test the car at Hockenheim, two weeks before the 24-hour race for touring cars at the Spa-Francourchamps circuit in Belgium. Then disaster struck at Hockenheim when test driver Helmut Kelleners crashed the car in a big way, and AMG's small group of overworked employees had to work day and night to repair the car for its debut. New drivers were found. They were German go-kart champion Hans Heyer and veteran driver Clemens Schickendanz. The pair used practice and qualifying rounds to work out fuel and tire consumption, and during the race counted on the pit crew of six to keep the car going. Their big red sedan finished the race first in class and second overall, and the AMG legend was born. The AMG car entered a total of only eight races, and although it was fast (it was clocked at 176 mph on the Hunaudieres Straight at the four-hour touring car race at Le Mans), it never repeated its earlier podium success. Racing rules changed in 1972, setting a displacement limit of 5.0 liters for touring cars. Its racing career over, in 1973 the AMG-Mercedes-Benz 300SEL 6.8 race car was stretched three inches, given a full 428-bhp engine and special high-speed tires, and was used by French aircraft manufacturer Matra as a stable platform to test the landing gear of jet fighter aircraft.