Review: 2007 Mercedes-Benz ML320 CDI Test Drive

Mercedes’ ML320 CDI midsize diesel SUV combines luxury with outstanding fuel efficiency. Careful with adding options, though, as they can really jack up the price.

by Lawrence Ulrich
ForbesAutos.com

Bad news first: If you live in California, Maine, Massachusetts, New York or Vermont, you can”t buy the Mercedes-Benz ML320 CDI, or for that matter, any diesel passenger car (as of 2007). Those states have set their own, stricter emissions rules, so even Mercedes” current diesels, the world”s cleanest, don”t pass muster.

The good news is that situation will change beginning in late 2008, when new technology “” and a new, ultra-clean diesel fuel “” will open the door to a wave of high-mileage, 50-state legal diesels from not only Mercedes, but Audi, BMW, Chrysler, Honda, Jeep, Nissan, Volkswagen and likely others.

Until then, buyers in 45 states can choose diesel engines as an option in Mercedes” M-, R- and GL-Class SUVs; its E-Class Sedan; or in the Jeep Grand Cherokee, which borrows Mercedes” technology. (Diesels are also available in heavy-duty, work-centric pickup trucks from Ford, Dodge and GM).

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For any of these diesels, the green icing on the cake is outstanding mileage, 20 percent to 40 percent better than a comparable gasoline model. In our test of the ML320 CDI, we saw a frugal 27 mpg on the highway and 24 mpg overall, compared to 20 mpg highway and 18 mpg overall in the gas-powered V6 ML350. (The EPA rates the diesel version at 21 mpg city/27 mpg highway, and the ML350 at 17 mpg city/21 mpg highway).

Based on the fuel-economy numbers we got during our test drive, the diesel ML would save a typical driver about $400 a year in fuel “” and that”s even accounting for the fact that diesel fuel typically costs more than premium gasoline.

Unlike with current hybrid models, those savings don”t come at a huge premium: The ML320 CDI costs just $1,000 more than the ML350.

A typical owner would hit the break-even point in about 2.5 years; from then on, the owner would pocket the savings. He or she would also make fewer trips to the pump: The ML320 CDI can travel more than 600 highway miles on a single tank.

Exterior

Released in 1998, the first generation of the Alabama-built M-Class was not a high point for Mercedes, with its staid minivan styling, poorly finished interior and truck-like ride and handling.

But the second-generation model, which debuted for 2006, is dramatically better: vastly more solid, stylish, luxurious and well-crafted.

The new body still seems to mix-and-match elements of an SUV, station wagon and minivan, but it also looks like a genuine Mercedes. There”s a pronounced wedge shape, sharply angled windshield, and of course that prominent three-pointed star emblem on the handsomely sculpted grille.

Importantly, the new M-Class adopted the unibody construction of a typical car, rather than the previous heavy, truck-style frame. That reduces weight, improves ride and handling and makes the M-Class less prone to squeaks and rattles.

The new version is nearly six inches longer, three inches wider, and slightly lower than its predecessor. Like most luxury SUVs these days, the Mercedes M-Class strikes a good balance between ride height and easy ingress/egress, especially for shorter drivers and passengers.

Interior

The Mercedes mystique continues inside, where the M-Class is as serene, luxurious and comfortable as one of the automaker”s sedans.

The back seat is strictly for two adults, with a hard center perch for a third body that’s best reserved for shorter trips. To expand cargo capacity, tug the rear seat cushion forward, then flip the seatback down (it”s split 60/40 for added versatility) to create a relatively flat load floor and about 72 cubic feet of storage, which is average for this class. Side and head (curtain) air bags are standard, and a rollover sensor can cinch the seatbelts and activate the curtain airbags in the event of a rollover.

A few issues came up during our test drive: Mercedes” cruise control stalk remains too close to the turn signal, leading you to grab the wrong one at times. The COMAND system that manages navigation, audio and other functions remains a bit cumbersome, with rows of tiny buttons along its display screen.

That screen slides open to load CDs into the six-disc changer.

Despite its relatively hefty price, the M-Class isn”t exactly bursting with standard luxury gear; even leather seats and the six-disc CD player cost extra. Our tester had some $14,000 in options, bringing the total tab to $59,425.

The biggest upsell, an $8,600 premium package, added most of the things that luxury buyers are after, including a Harmon/Kardon audio system with Sirius satellite radio; DVD navigation; rear back-up camera; sunroof; power liftgate; Bluetooth connectivity; Mercedes” TeleAid system; a power steering column; memory settings for the front seats; three-zone climate control; and power-folding mirrors.

A $1,450 exterior appearance package added 19-inch alloy wheels, blue-tinted glass, special taillight lenses and chrome on the door handles and exhaust pipes. Throw in stuff like leather seats ($1,520), the six-disc CD player ($440), and a package with heated steering wheel and heated front and rear seats ($1,360), and the ML”s price skyrockets.

Skip the Distronic adaptive cruise control, it”s way overpriced at $3,150.

Performance

If you haven”t experienced the kind of modern, high-tech diesels that are a staple of European roads, you”re in for a big surprise. While old diesels were notorious for their chug-chug sound and sooty, smelly exhaust, the new breed is incredibly quiet, clean and powerful. There”s not a trace of smell or smoke. In fact, several passengers who rode in the latest Mercedes models we”ve tested were completely unaware “” and amazed to discover “” that they were actually in a diesel vehicle and not a gas-powered car.

While diesels are close to overcoming their chief traditional vice “” high levels of soot and smog-forming nitrogen oxide emissions “” they actually produce substantially less global-warming greenhouse gases than gasoline engines.

And while some people grouse that diesel fuel is hard to find, the fact is that diesel is already being dispensed at about 40 percent of U.S. fueling stations, and that number is steadily growing. Hey, the big rigs and contractors” pickups have to fill up somewhere, too. So although diesel may not be on the street corner in your neighborhood, it”s likely to be at the next one down the road.

Bottom line, we”ve found that the difficulty of finding a diesel pump is often exaggerated.

Like most modern diesels, the Mercedes 3.0-liter V6 features turbo-charging and fuel-injection at extremely high pressures. The engine creates 215 horsepower, compared to 268 hp for the V6 gas model. But wait: The ML diesel”s trump card is massive torque, the pulling force that you feel when you tromp on the gas from a standstill and at city-driving speeds. The diesel”s massive 398 pound-feet of torque compares to just 258 pound-feet for the gas model.

Acceleration from 0-60 mph is identical at 7.9 seconds. Mercedes” new seven-speed automatic transmission is outstanding, and a permanent four-wheel-drive system is standard. There”s also a “hill-holding” function for starting off on inclines, and a downhill assist that lets the car creep down steep slopes without the driver having to touch the gas or brake pedal.

The diesel is just a bit louder at idle than the gas models, but it”s not at all obtrusive.

Regarding handling, the Mercedes M-Class veers toward comfort. It”s not as sporty and engaging on the curves as a BMW X5, but it rides beautifully and still feels accurate and confident on the highway.

At nearly $60,000, this ML320 CDI”s price becomes a bit eye-opening, especially when the outstanding and substantially larger GL-Class “” quite possibly the best performing, best-packaged large SUV on the market “” can be had for roughly the same price.

But going easier on the options can keep the ML”s out-the-door tab closer to $50,000. Consider the money you”ll save on fuel as icing on this luxurious cake.

 

Is the Mercedes-Benz ML320 CDI for You?

Buy the ML320 CDI if
You want to save fuel, save money and reduce global-warming emissions while still driving a powerful, luxurious SUV.

Keep Looking if
You live in California, Maine, Massachusetts, New York or Vermont where emissions rules preclude the sale of diesel passenger cars; you care less about mileage, and would rather stick with the gasoline version; although it emits fewer greenhouse gases, the higher concentration of smog-forming particulates from this vehicle”s exhaust give you pause; you need three rows of seats, in which case the Mercedes GL-Class is worth considering.

Who Fits?
Four adults comfortably and five in a pinch, with generous cargo space when rear seats are folded flat.

Closest Competitors
BMW X5, Cadillac SRX, Jeep Grand Cherokee Diesel, Saab 9-7x, Volvo XC90

Did You Know…
New ultra-low sulfur diesel fuel, mandated by the federal government and already available in Europe, burns much cleaner because more than 97 percent of its polluting sulfur has been removed. It”s being hailed by some environmentalists and government regulators as the most earth-friendly advance in automobiles since the removal of lead from gasoline more than 30 years ago.