The recently face-lifted M-class has enough sparkle and presence, what with its redesigned front bumper, flashy new headlamps, and shiny nineteen-inch wheels, to satisfy all who yearn for the three-pointed star. This ML320 BlueTec replaces the previous ML320 CDI and is powered by Mercedes-Benz’s all-new, so-called “clean” diesel, the first modern diesel engine from Mercedes that is approved for sale in all fifty states, including super-picky California, because it uses an AdBlue exhaust injection liquid that reduces NOx by some 80 percent. That is quite an achievement.
And it is quite a powertrain, with very quiet operation and virtually no indication to the user that it’s a diesel. Turn the key, and there’s just a slight hesitation before the 3.0-liter turbodiesel V-6 ignites and quickly settles into its almost indecipherable rhythm. Torque? Yes, nearly 400 lb-ft of it, giving you smart acceleration from stoplights (Mercedes claims a 0-to-60-mph time of about 8.0 seconds) and, of course, great towing capability: Mercedes says you can drag 7200 pounds of trailer and cargo behind you. With a 24-mpg highway fuel economy rating and a 25-gallon fuel tank, the ML320 BlueTec also boasts a 600-mile driving range. That alone is reason enough for many people to choose the ML320 BlueTec over its gasoline-powered sibling, the ML350, which is rated by the EPA at 20 mpg on the freeway, giving it an effective range of 500 miles.
Joe DeMatio, Executive Editor
For as long as the M-class has been around, I’ve struggled with the size and purpose, but remember, I own a Chevy Suburban that I use every inch of. But this is certainly luxurious, in the more simple, old-fashioned M-B sort of way. I especially like our test vehicle’s cabin, with its tasteful dark brown over taupe color scheme, rich wood accents, and straightforward gauges. COMAND is much simpler to navigate through than it used to be, and the seats are great. There’s the hedonistic one-touch tailgate open-and-close feature, and now…now there’s BlueTec. When gas prices again spike, as they inevitably will, we might come screaming back to diesel. And this would be a very nice diesel vehicle to own. It roars out of the gate like a big V-8 but with better fuel economy (so good, in fact, that I drove it all weekend and it still had a quarter-tank when I brought it back). This high-tech diesel engine doesn’t makes noises or stinky-poo smells, although you still have to fill it up at mostly stinky-poo pumps that get your shoes and hands all yucky.
I never could get a comfortable suspension setting from the optional $1600 Adaptive Damping system. In COMFORT mode, the annoying side-to-side shake on even fairly decent road surfaces made me nuts. In SPORT mode, the shake went away, but sharp road inputs felt like bad chiropractic adjustments. In either mode, handling was superb, I must say, encouraging me to really push it into curves and savor its comportment.
Jean Jennings, President & Editor-in-Chief
Most folks will never know what’s humming under the hood of the Mercedes-Benz ML320 Bluetec. The characteristic diesel rattle, smoke, and smells are gone. There’s no starting hesitation in frigid weather, and the tailpipe residue is gray ash instead of black soot. From idle to the 4500-rpm redline, the Bluetec V-6 sounds more like an electric motor than an internal-combustion engine.
A seven-speed automatic restricts the engine to its torque-rich 2000-to-3000-rpm band with rare excursions beyond 4000 rpm. The shift paddles are fun to play with but are unable to stop the transmission from upshifting well before the redline.
The Mercedes diesel V-6’s core components are an aluminum block with iron cylinder liners, aluminum heads supporting dual overhead camshafts and four valves per cylinder, and a forged-steel crankshaft. To achieve even firing and low vibration with this engine’s 72-degree V-angle, a split-pin crankshaft and a balance shaft are necessary. The electronically controlled common-rail injection system delivers two to five squirts of fuel per combustion cycle at 22,720 psi through piezo-electric injectors. Multiple injections quell the rattle while the ultrahigh delivery pressure fosters fast fuel vaporization and more complete combustion. Half of the intake ports are throttled at times to swirl the air entering the combustion chamber. A variable-nozzle device gets the turbo spinning and boost rising at low rpm. External emissions controls include an oxidation catalyst, a particulate filter, a valve to meter the AdBlue aqueous urea, and a selective catalytic reduction stage. To burn accumulated soot from the particulate filter, the exhaust temperature is periodically raised to 1100 degrees Fahrenheit by injecting extra fuel. The seven-gallon supply of AdBlue fluid is replenished every 10,000 miles during normal oil-change service.
Don Sherman, Technical Editor
2009 Mercedes Benz ML320 BlueTEC
Base Price (with destination): $49,475
Price as tested: $58,165
Adaptive Damping System – $1600
Rear Seat Entertainment System – $1850
P01 Package – $3850
-Rear View Camera, 40GB Hard-Drive with GPS Nav, SIRIUS Satellite Radio, HD Digital Radio, iPod Media Interface, harman/kardon LOGIC7 Surround-Sound System with Dolby digital 5.1, Power Liftgate, 115V AC Power Outlet
Heating Package – $1390
-Heated Leather Steering Wheel, Heated Front Seats, Heated Rear Seats
Fuel Economy: 18 / 24 / 20 (city/hwy/combined)
Size: 3.0L V6 24-valve Diesel Engine
HP: 210 HP @ 3800 rpm
Torque: 398 lb-ft @ 1600-2400 rpm
Transmission: 7-speed Automatic
– 255/50 R 19 all-season tires (size)
– 19″ Alloy Wheels