RENNtech Mercedes SLR McLaren 722 When Mercedes decided it was time to give the SLR supercar a boost, it created the Mercedes SLR McLaren 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 of the race. RENNtech Mercedes SLR McLaren 722 722mclarenmercedesrenntechslr in Public bookmarkswith 722autoautomotivecarscustommclarenmercedesnewsrenntechslrtuning