The R-Class is offered in two wheelbases, 2,980 mm (117.3 in) and 3,215 mm (126.6 in), the latter being the lone offering in the US.
Models using the BlueTec diesel engine were introduced for the 2009 model year in certain markets, with other markets getting Mercedes' BlueEFFICIENCY technology.
The R-Class scores "Good" in the Insurance Institute for Highway Safety (IIHS) front crash test. But was given an "Acceptable" rating in the side impact crash test before 2009 models built after September 2008 because the test dummy's torso faced excessive loads. For 2009 models built after September 2008, Mercedes modified the seatbelts and interior door trim and the IIHS rated the R-class "Good" overall in side impacts allowing the R-Class to receive the Top Safety Pick award.
Thatcham's New Car Whiplash Ratings (NCWR) organisation tested the R-Class for its ability to protect occupants against whiplash injuries with the car achieving the top 'Good' rating overall.
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