Mercedes (in full disclosure, a sponsor of MNN) was the first company to introduce a road-going diesel passenger car, in 1936. Rudolph Diesel patented his namesake engine in 1894, and began a collaboration with Mercedes, though he was not long for this world. “Diesel disappeared on a boat voyage from Belgium to England in 1913,” said Mercedes spokesman Geoff Day. “Nobody knows what happened to him.”
Diesel is gone but his engine lives on, even though he probably wouldn’t recognize the OM651 2.1-liter four-cylinder power plant in the GLK. It boasts twin turbochargers (high pressure for lower speeds, low pressure for high speeds) and direct injection engine for 200 horsepower and 369 foot pounds of torque. The car runs on today's ultra-low-sulfur diesel fuel, which has been required since 2010. A useful feature is 515 miles of cruising range. Here's some auto show video of it for a 360-degree view:
On BlueTEC diesels, there's an adblue injection system, which converts bad nitrogen oxides to harmless nitrogen and water to meet 50-state emissions. For you the driver it means you have to keep a tank topped off with a water-based urea system. It's not all that onerous--they refill it during scheduled maintenance.
This is Benz’ first four-cylinder diesel in the U.S., and the first in the midsized SUV segment here. The German companies have been the prime movers for American diesel (though Chevrolet and Mazda are also in the hunt), and that’s a reflection of the home market. In Western Europe, thanks in part to generous subsidies, 55 percent of the cars on the road are diesels, versus 2.6 percent here.
Like BMW (and both Audi and Volkswagen, too), Mercedes really wants Americans to feel the diesel love the way Europeans do. That’s why the car is priced so provocatively—they’re practically begging you to opt for a diesel. A gas-powered GLK350 is $37,090 (plus $905 dealer prep), and with the highly useful 4Matic all-wheel-drive system it’s $39,090. But the diesel GLK250 comes with 4Matic for just $38,590. That may tempt you to take it off-roading (see photo below), but respect the environment if you do.
The diesel car comes with such standard features as electronic traction control, electronic stability and attention assist. That’s important, because the optional features on this car can really add up. The loaded car I first test drove clocked in at $57,075 with the premium package, leather and multimedia, lighting and appearance add-ons. Mercedes is a leader in safety, so it will be your move when it comes to adding such potentially important systems as active blind spot or lane-keeping assist, active parking and adaptive high-beam assist.
The GLK250 diesel is rated at 24 mpg city/33 highway, and 28 mpg combined. That’s actually better than Audi’s competing Q5 Hybrid, which is 24/30 and 26 combined. Benz will offer the exact same drivetrain in an E-Class car just down the road, and if its fuel economy you’re after, that one should be 40 mpg or better on the highway, said M. Bart Herring, a Mercedes product manager.
My own result driving the GLK250 from woodsy Armonk, New York into Manhattan (mixed highway and local) was 33.9 mpg, which was pretty good. I’m a big supporter of clean diesels, but I should note that the fuel is usually more expensive at the pumps—though I note that this week it’s about the same price as premium fuel ($3.83 for premium, $3.88 for diesel).
I didn’t see an official zero to 60 time, but with the twin turbos the car is very fast off the line, and extremely quiet inside the cabin. If you don’t know it’s a diesel, the car won’t tell you. Once you’re up to speed there’s not a huge reserve of extra power, and that’s because this is a 2.1-liter four.
The interior is very tasteful in German earth-toned manner, and this new diesel should be right at home in the Westchester suburbs I drove it through. The styling is a little angular for my tastes, but since form follows function I’m sure it would grow on me—the storage space was cavernous and the folding rear seat very accommodating to tall passengers.
In the end, it comes down to how many potential buyers will be comfortable with a diesel drivetrain. It’s been a tough sell for Americans with bad memories of the bad old 1980s, when belching smoke, poor reliability (especially from the hastily done GM entries), and anemic performance was the norm. But attitudes are changing. My guess is that 20 percent of GLK sales will be diesels, but attractive pricing could push that number higher.
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