When Mercedes decided it was time to give the SLR supercar a boost, it created the SLR 722 edition. But don’t for a second think that number has anything to do with the car’s output. In fact, the supercharged 5.5L V8 engine puts out 650hp, a significantly lower figure than its 722 labeling suggests. The odd title comes from the 1955 Mille Miglia, where Stirling Moss and Denis Jenkinson beat out favorites from Porsche and Ferrari to take victory in a Mercedes-Benz 300SLR. The car was wearing the number “722,” which indicated the 7.22am starting time.

At least for the original, the number 722 had some significance, but as RENNtech’s Hartmut Feyhl puts it, “for most people, six-fifty is probably enough but you see that ‘722’ on the car and you start to want seven-hundred and twenty-two horsepower.” Feyhl is a former AMG staffer with over 12 years experience at the famous Mercedes tuner and has since started his own tuning shop, RENNtech performance.

For the extra power, engineers upgraded the stock intercoolers and replaced the intercooler pump with a RENNtech-specific unit that has close to double the capacity of the standard version. Intake temperatures are now 10 degrees Celsius cooler, which meant that boost pressure could be increased and thus the 722hp mark could be achieved. Pity the original propeller-style wheels were swapped with these much more ordinary 20 inchers.

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