Diesel is Back, and That’s a Good Thing

Oct. 15 (Bloomberg) — “Pee-yeew!” my dad would call out the open window, “You stink!” This was a 1970s-era ritual played out every time we passed a rattletrap diesel-powered car trailing black haze on the highway. Not kind, maybe, but true. Those suckers stunk up the place.  

Though I’m hardly the only American who has negative associations, diesel fuel has seen a major resurgence in Europe, the result of ultra-low-sulfur diesel and engines designed to negate emissions. The benefits are as much as 30 percent better fuel economy and 20 percent to 30 percent less carbon dioxide emissions.

Which brings us to Mercedes-Benz’s 2009 ML320 BlueTEC, a diesel-powered SUV that went on sale this month for $49,475. The previous version, the ML320 CDI, was released two years ago and could only be sold in 45 states. (New York, Massachusetts and California were not among them.) This baby’s clean enough to be offered in all 50. (The larger GL320 SUV and minivan-like R320 are also available with BlueTEC. Volkswagen, Audi, Honda and BMW also have diesel models out or on the way.)

It’s a big day: Not only will diesel have a chance to redeem itself in my eyes, with any luck so will the ML320. First released as a 1998 model year, reliability issues have plagued the M-Class like the word “`potato” haunts Dan Quayle. Consumer Reports has a number of model years in its “used cars to avoid” list and has called the reliability “disappointing.”

Face Lift

The line got a big redesign in 2006, which fixed many issues like the poor interior. The 2009 models see a minor face lift, mainly with aesthetic tweaks to the front and interior upgrades and options. J.D. Power & Associates gives the 2008 M-Class very high scores for predicted reliability.

“This is a perfect mom vehicle,” says my passenger. “I’d want it if I had kids.” She’s right. The M-Class never really had pretensions of being a rough-and-ready off-roader like the Jeep Cherokee, nor a speedy SUV like the BMW X5, first released in 2000. (If you’re looking for a high-powered M-Class, the 503- horsepower ML63 AMG can be yours for more than $90,000. Its gas mileage of 11 mpg in the city might sting, though.)

The ML320 has the high seating position many SUV buyers like, holds five adults and has 72 cubic feet of storage. The bland styling is probably intentional, benign and friendly rather than beefy and aggressive. A family vehicle all the way.

No Belching

Other than the BlueTEC badge on back, there’s no tip-off that this is a diesel. No belch of black smoke out the tailpipes, no disquieting rumble from the engine. And no stink.

The ML320 has a turbocharged V-6 engine that runs on the ultra-low-sulfur diesel now available in the U.S. The exhaust treatment system uses a particulate filter and oxidation catalytic converter to reduce nitrogen oxide emissions by a huge amount. (Nitrogen oxide contributes to smog.)

The end result is a diesel vehicle that doesn’t seem like an old-school diesel whatsoever. Jump in, turn it on and get moving.

And from a standstill, move it does. Diesels are renowned for low-end torque, and the BlueTEC is flush with 398 pound-feet of the stuff. It jumps up with real intent, getting its 5,000 pounds moving. At about 35 mph it slacks off, with a 0 to 60 speed of 8 seconds or so. Yet in city traffic that off-the-line power is very welcome.

Horsepower is rated at 210, less than the 268 hp on the gas- powered ML350, which costs $47,975. (The $56,675 ML550 has a V-8 and 382 hp.)

The BlueTEC gets 18 mpg city, 24 highway — not as good as the new Cadillac Escalade Hybrid, which attains 20 in the city, but it bests the regular ML350 by 3 mpg and 4 mpg, respectively. Mercedes says you can get 600 miles of combined driving on a single tank.

Tall Car

The ML320 drives like a very tall car. It’s easy to handle around town and generally makes few demands of its driver. Though it has a sport setting, the suspension is geared for comfort. On a section of New York City’s FDR Drive where metal plates serve as the driving surface, I rumbled straight over and barely bounced around.

The seven-speed automatic transmission works quietly in the background, but you can also control gears with paddles behind the wheel. As an all-wheel-drive, the ML handles fine on the freeway and is decently planted on curves, though its rival the BMW X5 is more agile and fun to drive.

While the ML320 has steel skid plates on the underbody and electronic functions like hill descent control, don’t expect to see one on the Rubicon Trail anytime soon. Nobody really expects you to take it out four-wheeling.

The interior is standard Mercedes. There’s nice use of leather and stitching, and the GPS navigation is easy to operate. You can add as many high-tech options as you care to.

All in all, the ML320 seems to have evened out in its middle age. The option of the diesel may not make it exciting, but it’s more enticing. It’s a shame that the price of diesel, which can be more than 40 cents a gallon higher than gasoline, will discourage many buyers.

One thing even my dad would agree on: It certainly doesn’t stink.

The 2009 ML320 BlueTEC at a Glance

Engine: Turbocharged V-6 with 210 horsepower and 398 pound- feet of torque.

Transmission: Seven-speed automatic.

Speed: 0 to 60 mph in about 8 seconds.

Gas mileage per gallon: 18 city; 24 highway.

Price as tested: $56,000.

Best features: The fuel efficiency and low-end power.

Worst feature: Bland styling.

Target buyer: The family driver who wants better gas mileage in an upscale package.

(Jason H. Harper writes about autos for Bloomberg News. The opinions expressed are his own.)