2007 Mercedes-Benz ML 320 CDI Review

There’s a fight brewing between environmentally conscious car buyers. In one corner you have hybrid enthusiasts. Clean and electric, they tout their cars’ fuel efficiency and technology. They also get nifty stickers that let them drive alone in carpool lanes.

In the opposing corner you have diesel. Once dismissed in the U.S. as too noisy, stinky, sooty and costly, new diesel technology from Europe is once again gaining traction. New diesels have lower emissions than gasoline, and new technology combined with cleaner U.S. diesel fuel is spurring a resurgence of interest in the technology.

For now, diesel passenger cars in the U.S. are almost exclusively European in origin, and one brand that is most strongly associated with the fuel is Mercedes-Benz. We drove a Bluetec E320 not too long ago and were generally impressed with the new-tech solution to the age old problems of diesel soot and odor. Mercedes has also applied an older diesel technology to its M-Class crossovers. Redesigned with sharp new clothes a couple years ago, the ML is already a class leader. With diesel technology under the hood, we wanted to know if it was a technology and environmental leader as well.

Our test vehicle was a 2007 Mercedes-Benz ML320 CDI. The CDI refers to the common-rail direct injection system used in the ML320’s engine; the high fuel pressure lines and quick-reacting injectors act to lower emissions, improve noise levels and smooth the idle. The base price of the ML320 CDI was $44,455 including the $775 destination charge. Options included the $700 Capri Blue paint, the Premium Package at $8,600, leather seating for $1,520, the exterior appearance package for $1,450, and the heating package – which included a heated steering wheel in addition to bun warmers on the front and rear seats – for $1,360. Overall our test car came in at an eye-popping $59,425.

Page 2

Hear “diesel” and you think “torque.” The CDI engine in the ML320 delivers in spades, producing the most torque of all ML models except for the AMG ML63. The torque peak is also ridiculously low, a mere 1,400 rpm is where it starts, so you have prodigious thrust right off idle. The horsepower peak of 215 comes at the engine’s 3,800 rpm redline, but really, torque is where it’s at in this engine. If you want to drive fast, leave the engine in higher gears and shift early; you’re rewarded with snappy acceleration. It will spin willingly to redline, but it’s a waste of time; down low is where the fun is.

OK, so it’s fun, but does it smell funny? Not usually, however this isn’t a Bluetec, so the engine does have a touch of the old-school diesel drawbacks. We noticed the occasional whiff of diesel exhaust at idle, and it’s definitely not as quiet or smooth as the Bluetec. However, it’s still very acceptable, especially considering the performance benefits on the street. We were surprised, however, that the CDI only managed 21 mpg during its tenure with us. That’s better than the average for this class, but we expected more miserly consumption.

The seven-speed transmission can shift for itself or, if you’re so inclined, manually with buttons mounted on the back of the steering wheel spokes. Leave it alone and the ML320 shifts early; normally this is a complaint, but here it keeps you in the fat part of the torque band. Pick your own gears and you’re rewarded with quick upshifts. Downshifts are mostly shock-free, thanks to the short ratios, but there is still a delay between the control input and the actual gear change.

The suspension on the ML320 has two modes. The Comfort mode is exactly what it says, and you’re rewarded with that lovely Mercedes-Benz ride. In fact, it may skew a little too far toward soft, as the suspension felt a little underdamped for some of us.

Then there’s the Sport mode. Push the button on the dash and you’re rewarded instantly with firmer damping and a much more controlled ride. During our canyon run with the ML, we switched back and forth between the two modes, and the difference was stark. In Comfort, the ML was lazy, lolling on its side during corners, tires protesting in a decidedly non-sporting manner. Switch it to Sport and the suspension instantly firmed up to the point where the car was begging you to push it in corners. Often, adjustable suspensions are subtle at best (imperceptible is a better term), but this one really made a tremendous difference. The downside, of course, is that the Sport mode is uncomfortable on broken pavement or expansion-jointed concrete. An automatic setting lets a computer decide between the two, but we mostly just switched it ourselves.

Steering was good, with light effort and decent feedback, but the ratio is slow so you have to take your hands off the 10 and 2 o’clock positions to use the shifter buttons in aggressive driving, defeating the whole point of them.

This vehicle has a huge dash, which can be difficult to see over. Visibility to the sides is much better, but only when you use your eyeballs; the outside mirrors are on the small side. A quick over-the shoulder is impaired by the huge C pillar and thick D pillar; this is a common problem in unit-body crossover vehicles like the M-Class, but it’s particularly egregious here. Thankfully the view directly out back is good thanks to the large rear glass and second-row head restraints that retract almost flush with the seatback. The backup camera helps considerably when reversing. However, maybe Mercedes-Benz (and several other manufacturers) should license Volvo’s BLIS blind-spot checker.

“Diesel-powered” and “crossover” don’t sound like primary ingredients for fun, but the ML320 CDI is surprisingly rewarding to drive. It’s not the best handler in its class; that would go to the Acura MDX, Audi Q7 or maybe the BMW X5. However, once you push the right buttons on the console and recalibrate your shift points it can be a pretty fun vehicle to snort around in.