2008 Mercedes-Benz M-Class Review

More features, more power.

Introduction

The Mercedes-Benz M-Class SUV is just the right size and is set up well for many families. It isn't so large that it's cumbersome or hard to park, but it comfortably seats five and carries plenty of stuff. As daily transportation, it doesn't feel like a truck, and it won't beat its driver or passengers up. Yet it has the potential for some fairly serious off-road adventuring, and it can tow up to 7,200 pounds. The M-Class is more than powerful enough in any of its variations. And it offers the safety equipment, luxury accoutrements, style and smooth finish expected of a Mercedes-Benz.

For 2008, the M-Class line replaces the ML500 with the more powerful ML550. Also called the M-Class, the lineup continues to include the ML350 with its gasoline V6, the fuel-efficient ML320 CDI diesel, and the ultra-high performance ML63 AMG.

With the ML320 CDI, you can forget just about everything bad you knew about diesels. It's smooth and quiet, and clean. It gives up nothing to the standard, gasoline-powered ML350. It's equipped identically, except for its diesel engine. The 3.0-liter diesel V6 generates 398 pound-feet of torque, comparable to a large-displacement V8, and brings a substantial improvement in fuel economy.

The ML63 AMG features a hand-built V8 that generates 503 horsepower with AMG tuning and enhancements to match all that power. Though considerably more expensive than other M-Class models, the ML63 AMG is a true high-performance machine. Its 6.2-liter V8 is hand-built by a single technician. It bursts from 0 to 60 mph in 4.8 seconds, according to Mercedes, with top speed electronically limited at 155 mph. Plus, it comes with the full load of luxury features.

With increases of 80 horsepower and 55 lb-ft of torque, the new ML550 reaches 60 in 5.6 seconds, more than a second quicker than the previous ML500. It sports the same front end as the ML63 without all the amenities and super-sport equipment, and starts at roughly $30,000 less than an ML63.

The original M-Class helped make luxury SUVs a familiar part of the automotive landscape. Completely redesigned for the 2006 model year, this second-generation M-Class is better than the original in every way. It's roomier, more comfortable and more car-like in its bearing. Its wheelbase is almost four inches longer, and its body three inches wider, all to better accommodate larger Americans inside. In the bargain, the coefficient of drag, or Cd number, has dropped from brick-grade to a sylphlike 0.34, on par with many passenger cars that are much lower to the ground. This means quieter highway travel and better fuel economy.

In place of the original body-on-frame, truck-style design, this second-generation M-Class has welded unibody construction with isolated front and rear subframes, a technique that emphasizes rigidity, decreased vibration and lower weight. The unibody also reduces its overall height, making it easier for families to get in and out. The M-Class has given up any pretense to being a large-family vehicle. The optional side-facing rear seats from the old model are gone (they weren't very good anyway), so the M-Class is strictly a five-seater. You'll want to look at the GL-Class for seven-seat accommodations in a Mercedes SUV.

The second-generation M-Class introduced for 2006 brought a new look and larger size along with a double-wishbone front suspension and four-link independent rear suspension emphasizing sedan-style dynamics. Yet with a two-range transfer case on most models, and a sophisticated control program for the full-time all-wheel-drive, the M-Class can get its driver through some tricky off-road situations.

M-Class buyers will pay a premium over many other comparably equipped luxury SUVs, but those who appreciate the cache and engineering strengths of the Mercedes brand will find plenty to like here.

All 2008 models come standard with a sunroof, blue window tint and 19-inch wheels.

Lineup

The 2008 Mercedes M-Class includes four models. Each is equipped with a seven-speed automatic transmission and electronically managed 4ETS fulltime all-wheel drive. The primary distinguishing feature for each model is its engine.

The ML350 ($43,650) is powered by the latest-generation Mercedes 3.5-liter V6, generating 268 horsepower. It comes with vinyl upholstery, automatic headlights, power seats, sunroof, 19-inch wheels and an eight-speaker stereo with CD.

The ML320CDI ($44,650) is equipped similarly but with the 215-hp 3.0-liter diesel V6 rated at 398 pound-feet of torque.

The ML550 ($52,400) gets the latest four-valve 382-hp V8 and more standard features. These include heated, leather covered front seats, walnut burl trim, rain-sensing wipers and Tele-Aid emergency communication. The ML550 also includes more potent brakes and AMG front styling.

The ML63 AMG ($86,650) features a 6.2-liter V8 that generates 503 hp along with an AMG transmission, AMG shocks and suspension tuning, high-performance P295/40ZR20 tires on 20-inch wheels, AMG brakes, an air dam and other aerodynamic aids, AMG instruments, harman/kardon Logic7 CD6 audio with 12 speakers, and leather upholstery.

Options include Distronic radar-managed cruise control ($2,200), Parktronic obstacle warning ($770), dual-screen rear-seat DVD entertainment system ($2,670), Keyless Go starting ($1,100), iPod integration kit ($375), CD6 changer ($450). Three packages are available, designated Premium I that includes DVD navigation ($3,650), PII ($5,550), and PIII ($8,500), with exact content tied to the model. Last year's AMG Sport Package ($4,550) is standard on M-Class V8s.

Safety features on all models includes two-stage front airbags for the driver and front passenger, side-impact airbags front and rear (torso protection) and curtain-style head protection airbags. A rollover sensor can activate both the seat-belt tensioners and curtain airbags if the vehicle senses an imminent rollover. An Electronic Stability Program comes standard along with advanced anti-lock brakes with electronic brake-force distribution. A tire pressure warning system is also standard.

Walkaround

The 2008 Mercedes-Benz M-Class styling tweaks vary between V6 and V8 models. From the emotional perspective, the front end is bold, interesting and aggressive, with ventilated grille bars, a power-dome hood design and wild-looking integrated headlamps. In profile, the wheel arches loom large and prominent. There's an unmistakable character line rising front to rear, and a forward-slanting C-pillar that frames trapezoidal rear side glass.

On the practical side, the M-Class body is much more aerodynamic. Its drag coefficient, or Cd, measures 0.34. That's closer to the average sedan than the typical slab-sided SUV. The lower the number, the less noise generated as air flows over the vehicle, and the less power required to move the ML at a given speed.

Some improvements aren't readily apparent to the eye. A new-fangled scratch resistant paint, embedded with thousands of flecks of ceramic, is standard. It should be welcomed by those owners who actually decide to challenge overgrown trails, or those who share their garages with kids, toys and bicycles. There's an optional power liftgate operated with the key fob, and several cargo organizing devices available as accessories.

The ML63 AMG is readily distinguished from other M-Class models. If its 20-inch spoke rims aren't a dead giveaway, check the ML63's more aggressive front and rear aprons, flared fenders and deeply sculpted AMG side skirts. The ML63 also features unique tinted taillights and two sets of twin-chrome exhaust tips.

Interior

Inside the Mercedes-Benz M-Class, the dashboard, door panels and seats complement the aggressive exterior design nicely. Wood, leather, plastic and metal finishes are generally top-drawer, as they should be at this price.

Four huge, round air vents spread across the dash panel, which is dominated by a deeply hooded instrument cluster with sharp graphics and prominent chrome trim around the tachometer and speedometer. A central information window between the gauges can be programmed to supply about as much driving and maintenance information as one driver can stand to absorb.

The steering wheel has a nice, thick rim that's reassuring when driving off road. We're fond of the optional steering wheel that's finished with the top half in wood and the bottom half in leather, but some drivers don't like wood or mixed materials on their wheels. The center hub houses four sets of controls for information, telephone, navigation and entertainment systems. Wipers are stalk-mounted to the left of the column, while primary climate and audio controls are in the center stack above the console. The center stack is dominated by the elements of the COMAND system and a 16:9 LCD display which incorporates entertainment, telephone, and navigation displays.

The M-Class features an electronic gear selector that's making its way into all Mercedes models. It's an easy-to-reach short stalk on the right side of the steering column, with simple up-down movement for reverse and drive. Alternate shift buttons, which allow selection of a specific gear, are located on the back of the steering wheel hub, right where fingers wrap around the spokes. It's a good system, and eliminates the conventional gear selector from the center console, making more room available for elegant design and function in the form of an award-winning cupholder.

The power seat controls have been relocated from the door to the outboard side of the seat bottom. We can fathom no reason for this change except the cost trimmed by eliminating the remote switches. It's certainly a less convenient arrangement.

The front seats themselves, including the standard seats in the ML350, are all-day comfortable.

The ML63 AMG has heavily bolstered sport seats upholstered with Nappa leather and an Alcantara insert across the shoulder bolsters. Its entire dashboard is wrapped with leather. The ML63 also features a leather-wrapped sport steering wheel, unique instruments with AMG graphics and stainless-steel pedals with rubber studs.

The rear seats in the M-Class aren't as supportive as the front seats, but they are roomy, and much roomier than in the truck-based, first-generation models. Most of the newly created space in this second-generation M-Class translates into more knee and legroom for rear-seat passengers.

Cargo space is expanded by folding the rear seat, which increases storage space from 29.1 cubic feet to 72.4 cubic feet. The rear seat folds fairly easily, and is split 60/40. The load height in back is high, as it is with many SUVs, but M-Class offers nearly as much cargo-hauling room as full-size truck-based SUVs.

Driving Impression

In any variant, the Mercedes M-Class will do just about anything most owners demand, on road or off road. Acceleration performance varies across the model line, ranging from better than adequate in the ML320 and ML350 to race-like with the ML63 AMG. Ride quality on pavement is never rough, even in the more stiffly suspended ML63, which features the AirMatic air suspension as standard equipment.

The diesel engine represents the state of the art and we really like it. Available in most states, it's as clean as the ML's gasoline engines and gets much better fuel economy. With this engine, there is no black soot, no sulfur smell and no loud, clattering noise. At idle the diesel in the ML320 CDI is nearly as quiet as the gasoline engine in the ML350, and that's when you're standing outside next to the vehicle. Inside, a driver is hard pressed to tell any difference between the gas and diesel engines, measured by noise or vibration. The only obvious difference is that the diesel shifts to a higher gear under full-throttle acceleration sooner than the gas engine to take advantage of its torque and goes farther on a tank of fuel.

Mercedes reports identical 0-60 mph times of 7.9 seconds for the both the ML320 diesel and the ML350. Yet that doesn't tell the whole story, because in short bursts the diesel actually accelerates more quickly. Its whopping 398 pound-feet of torque. compared with 258 pound-feet for the ML350, comes across as a neck-whipping burst of acceleration, and the turbocharging maintains power in high-altitude environs. And for this the diesel buyer gets a fuel economy improvement of 30 percent or more in real-world driving. We're perfectly happy in the ML350, but if diesel were readily available on our appointed rounds, we would choose the ML320 CDI over the ML350.

The ML550 is more fun to drive. The 5.5-liter V8 engine will take this 2.5-ton SUV from 0-60 mph in less than 6 seconds flat, and then settles down to a background burble by the time you reach seventh-gear overdrive. The seven-speed automatic offers a manual-shift mode, and it's the best automatic Mercedes has built. It's flexible, in that it kicks down to a lower gear more quickly than its predecessors, and it almost always keeps the engine in the most productive part of its power band. Yet its overdrive top gear makes for quiet high-speed cruising and better fuel economy.

During several days of hard driving in mountainous, sinuous terrain, we found the ML550 a hoot. The suspension is good at minimizing body roll in high-speed corners, and it smoothes dips and potholes well. The optional AirMatic suspension we tested can be downright supple, which trucks aren't supposed to be. The larger standard 19-inch wheels and tires and the power rack-and-pinion steering deliver a nice feel of the road, and quick reactions when necessary. At high speeds through mountain passes, the ML550 leans over a little, takes a set, and then grabs the ground and turns the corners.

Critics have complained with some justification about the electronically actuated and modulated Sensotronic brake system that Mercedes-Benz has been feeding gradually into all of its models over the last few years. We're getting used to them, and they'll stop the M-Class right now without much pedal effort. They've also improved considerably since they were first introduced. Yet they still don't have the smooth, linear feel of the best mechanically actuated brake systems. Nice smooth stops can be tricky without practice. We prefer the brakes in the Mercedes cars that do not have Sensotronic.

Off road, the ML550 and ML63 AMG offer the advantages of two significant features: a Downhill Speed Regulation software control that maintains the 4-12 mph downhill pace you set through the wheel controls, and a Start-Off Assist that keeps the vehicle from drifting backward in Drive or forward in Reverse on steep hills. Very handy, indeed, and eas.

Summary

The Mercedes-Benz M-Class offers a nice balance. It's not as stiff and unforgiving as some SUVs, nor as mushy on and off road as others. It has reasonable off-road capability and good towing capacity, but it's never a chore to drive during the more mundane daily tasks most drivers will undertake. Its choice of four engines is a plus, allowing owners to tailor priorities from high mileage to high performance.

New Car Test Drive contributor Jim McCraw filed this report from Provence, France.