The 2009 Mercedes-Benz R-Class is more of a workhorse than a thoroughbred.
About the new BlueTEC engine Edmunds says, “The diesel power plant is unfortunately a mixed bag. You can't ignore 398 lb-ft of torque, of course — the R320 really lunges forward once the Bluetec is on boil. However, it takes far too long for the transmission to act when you floor the gas from a stop. There's an exasperating delay (one-one thousand...) while the seven-speed slushbox unhurriedly mulls over your command, rather than the instantaneous turbodiesel torque we'd expect.” MyRide.com, however, views the performance of the R320 a little differently. “The R320 BlueTec gets to it as soon as you put your foot in the throttle, and stays at it all the way up to 2,400 rpm.”
Buyers have a choice between "a pair of eminently capable but relatively uninspiring power plants," reports Edmunds, which according to Cars.com are "a 3.5-liter V-6 in the R350 [that] develops 268 horsepower and 258 pounds-feet of torque," and the turbodiesel R320, which "produces 221 hp and 398 pounds-feet of torque." In the opinion of ConsumerGuide, the latter Mercedes-Benz 2009 engine "suffers brief turbo lag, then accelerates quickly."
Estimates by the EPA are 15 mpg city and 19 mpg highway for the 2009 R350 4Matic and 18/24 mpg for the R320. These figures are lower for ConsumerGuide, which determines that "an R350 averaged 17.6 mpg, requires premium-grade gas."
ConsumerGuide testers find that "the transmission in one test model periodically suffered jerky gear changes at low speed." Kelley Blue Book remarks that it delivers "seamless shifts, always finding just the right gear when needed." Cars.com states that both Mercedes-Benz R-Class engines "team with a seven-speed automatic," which "is able to skip as many as three gear ratios during downshifts to get the transmission in the proper gear."
For those concerned with braking power, Kelley Blue Book proclaims that stopping the Mercedes-Benz R-Class "is...no problem with its 13.8-inch front brake rotors and standard ABS and Brake Assist features." Cars.com comments that Mercedes-Benz 2009 "steering feels just right for this new class of car, and it requires moderate effort with utterly satisfying response," and ConsumerGuide attests it "acts more like a station wagon than an SUV," adding that "the steering is impressively linear and accurate, though some drivers may prefer a weightier feel." Car and Driver reports that the 2009 Mercedes-Benz R-Class offers "competent handling that no one could call sporty"; they say it "feels remarkably agile, [and] the AMG-tuned suspension is firm without being too harsh," noting that the "steering has a heft to it that serves as a reminder of the mass being hustled around."