Avg. Price Paid:$16,029 - $32,932
Original MSRP: $44,000 - $87,000
MPG: 15 City / 20 Hwy
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2008 Mercedes-Benz M-Class Performance

This performance review was written when the 2008 Mercedes-Benz M-Class was new.

Reviews are generally positive about the performance of the 2008 Mercedes M-Class, which includes the world's first-ever seven-speed automatic transmission in an SUV. "Its ride is smoother and its handling is more poised than the best of Detroit's truck-based sport utilities," says the New York Times.

The 2008 Mercedes M-Class is "unusually pleasant to drive," according to USA Today, and the majority of reviewers agree. "Both engines provide good acceleration and the vehicle hugs curves and absorbs bumps admirably," says the Detroit Free Press of the V6 and V8. Similarly, Kelley Blue Book praises the Benz's highway ride, noting it's "as smooth as you'd expect from any of the automaker's stately sedans, with the added benefit of being able to negotiate large rocks (or parking blocks) with exceptional composure. It's this silkiness that makes the SUV's confidence-inspiring cornering ability just that much more impressive."

Acceleration and Power

The base M-Class, the ML350, is powered by a 3.5-liter V6 engine, which generates 268 horsepower and 258 pound-feet of torque. According to Mercedes, the ML350 surges from 0 to 60 mph in 8.2 seconds. The ML320 CDI, which debuted last year, is equipped with the 215-horsepower 3.2-liter V6 engine -- a diesel, which is unique to its class. The ML550 boasts an all-new 5.5-liter 382-horsepower V8. Finally, the ultraluxury ML63 AMG, also new last year, features a 6.2-liter V8 that generates a whopping 503 horsepower.

Most reviewers agree that the ML350, though the least powerful of the M-Class models, is more than adequate. Kelley Blue Book says, "Opting for the lower-priced, higher-mileage ML350 won't leave you feeling short-changed in the power department." Edmunds agrees but also points out a deficit, noting, "In terms of acceleration, the ML350 possesses plenty of passing power, but feels a bit shy on torque from a stop." For more punch, reviewers recommend shelling out for the V8-powered ML550, which Mercedes says goes from 0 to 60 mph in 5.6 seconds. Cars.com offers high praise for the updated engine. "Calling this SUV 'fast' is an understatement," they say, adding, "This muscle SUV had me flooring it whenever I could to get the engine to come to life." Edmunds says the new engine offers "brisk performance."

According to the Environmental Protection Agency, the ML350 is rated at 15 mpg in the city and 20 on the highway, whereas the ML550 gets 13 in the city and 18 on the highway. But Autoweb.com feels that the ratings "are still atrocious ... A reasonable real-world average is probably three miles less for each, not much efficiency during a time when fuel economy is a growing priority among shoppers." All M-Class models take premium gasoline, with the exception of the ML320 CDI, which takes diesel gasoline and is rated at 18 mpg in the city and 24 on the highway.

All four models feature the world's first seven-speed automatic transmission, which Auto Mall USA calls "the best automatic Mercedes has built." USA Today says, "Five speeds are common, six exemplary, so Mercedes' seven-speed gearbox is a bragging point. To manually use those seven gears, you tap buttons on the back side of the steering wheel (the side toward the front of the vehicle). That works dandy." But MSN notes, "The stalk can be tricky to use if a driver is in a hurry. For instance, it requires more than lazy concentration to select a gear, and the 'park' gear position is gotten by pushing in the stalk."

Automobile Magazine also finds fault, noting, "Unfortunately, this electronic manu-matic erroneously believes it's smarter than the driver. Upshifts, want them or not, are automatic at the 6400-rpm redline ... The theory is that no driver should be left hanging during a passing maneuver, needing an upshift to muster more speed. Our contention is that any driver resourceful enough to choose the manual mode should be able to punch the button on cue."

Handling and Braking

The 2008 Mercedes ML350 features power rack-and-pinion steering that receives mixed reviews. "Test drives on twisting mountain roads showed the M-Class to have quick steering with Mercedes' slightly heavy, but reassuring, feel," says MSN. Autoweb also speaks highly of the handling, noting, "Tight maneuvers and U-turns are easy, thanks to a decent turning radius" -- one that, at 38.6 feet, is smaller than the X5, Escalade and SRX, according to the Detroit Free Press.

Others, like Automobile Magazine, disagree: "The steering is slow and slightly numb to the touch, discouraging maneuvers that might upset a copasetic cruise." Edmunds calls the steering precise but says it "doesn't offer much feedback and feels a little dead in the center." To improve steering feel, reviewers recommend adding the optional AirMatic suspension package, which includes speed-sensitive power steering and comes as part of the P3: Premium III Package.

The M-Class features a body-on-frame structure with twist resistance, giving it a solid feel. A majority of reviewers are pleased with the fully independent front and rear suspension, which the New York Times calls "firm by American standards, but not harsh or floaty ... Yet at no reasonable speed was the handling anything but superbly balanced." Kelley Blue Book also praises that the stiffer chassis "helps eliminate rattles and vibration." Automobile Magazine, however, doesn't like the "floaty feeling, which should be a hit with customers moving up from Buicks, but everyone else should exercise this escape clause: add the optional AirMatic suspension package that includes speed-sensitive power steering, air springs, and three-way adjustable dampers." The special suspension increases ground clearance up to 11.5 inches and offers several settings --sport, normal and comfort--to change the driving experience based on the terrain.

The ML350 includes an electronically modulated Sensotronic brake system, which most reviewers agree "supplies a sure-footed pedal and stops this SUV quickly," according to Edmunds. Though reviewers say the new electronic system takes practice to use, MSN's reviewer says, "I soon got used to it and appreciated the strong brakes. Road manners were very sporty for a heavy SUV." But Auto Mall USA has a criticism, commenting that the brakes "still don't have the smooth, linear feel of the best mechanically actuated brake systems. Nice smooth stops can be tricky without practice." Cars.com is perhaps the harshest critic, calling braking "the one failing in the M-Class' performance." They add the, "brakes stopped the car, but the mushy brake pedal feel led to poor response at almost every stop sign, light or congested road."

All-Wheel Drive

The Mercedes-Benz M-Class has permanent four-wheel drive using a system that diverts power to the wheels that can grip in necessary situations. The system works automatically, requiring no action from the driver. The New York Times calls it a "clever four-wheel-drive system that will pull you through even if three of the wheels have no traction." U.S. News reviewer Rick Newman calls the M-Class "a fully qualified off-roader too, with full-tilt-boogie four-wheel drive instead of less rugged all-wheel drive. Options, like specially modified off-road anti-lock brakes and an air suspension system that raises ground clearance, will convince die-hard trail buffs."

A standard one-button off-road driving program allows the driver to simultaneously engage programming recalibrations of the traction system, anti-lock brakes, engine management, and automatic transmission. In addition, all M-Class models come with downhill speed regulation, which automatically modulates the throttle and brakes and maintains a preset crawl speed when descending hills. A hill-start assist function helps prevent unwanted vehicle rollback when taking off from a stop on an incline by automatically maintaining brake pressure for approximately one second after the driver releases the brake pedal.


All M-Class models are rated at 5,000-pound towing capacity with the optional Class III trailer hitch. Auto Mall USA says, "We have little doubt that three of the four, including the new M320 diesel, would be up for the job (the diesel generates as much torque as a large displacement V8). We'd have some doubts about the gasoline V6 in the ML350, however." The reviewer recommends the ML320CDI or ML550 for towing substantial loads. Kelley Blue Book also notes that the ML320 CDI diesel is the way to go for those who expect to tow frequently because it has "the towing capability of a V8 with the fuel mileage of a frugal four-cylinder."

Performance Options

ML350 V6 base model

The base model comes standard with a 3,498-cc double overhead cam 24-valve V6 engine. It puts out 268 horsepower and 258 pound-feet of torque. The engine is paired with a seven-speed electronically controlled automatic transmission with Direct Select shifter.

ML320 V6 CDI Diesel

The diesel model comes with a 2,987-cc 3.0-liter DOHC 24-valve V6 engine. It puts out 215 hp and 398 pound-feet of torque. Like all M-Class models, the engine is paired with a seven-speed electronically controlled automatic transmission.

ML550 V8

The ML550 comes with a new 5.5-liter V8 engine that makes 382 hp and 391 pound-feet of torque. Like all M-Class models, the engine is paired with a seven-speed electronically controlled automatic transmission.


The ultra-performance ML63 AMG comes with a 6,208-cc DOHC 32-valve V8 engine. It puts out 503 hp and 465 pound-feet of torque and includes an AMG-modified engine management system. The engine is paired with a special AMG Speedshift seven-speed automatic transmission.

Review Last Updated: 2/17/09

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