After a lunch of bruschetta, pizza, and gelato, which is an ironic way to fuel up for testing a German car, Mercedes-Benz product manager Bart Herring gets straight to boasting. “No one is better positioned to bring diesel models to the market,” he says. “Diesel is very well suited to what people want.” Even setting aside Herring’s praise, the new 2013 Mercedes-Benz GLK250 BlueTec 4Matic is clearly something unique. Not only is it America’s only diesel compact crossover, it also handily tops its segment in fuel economy.
The 2013 Mercedes-Benz GLK250 returns 24/33 mpg (city/highway), giving a cruising range of 515 miles per tank. The existing GLK350, which has a 302-hp gasoline V-6, manages just 19/24 mpg with all-wheel drive. No other compact luxury crossover comes close to the BlueTec’s ratings, even those with thrifty 2.0-liter turbo-four gas engines like the Audi Q5, the BMW X3, and the Range Rover Evoque. None of those competitors can crack 21 mpg in the city and 28 mpg on the highway when fitted with all-wheel drive. Only hybrids come close: the Q5 hybrid returns 24/30 mpg, yet it’s $12,300 more expensive than the Mercedes, while the Lexus RX450h manages 30/28 mpg but costs $9110 more. In other words, the GLK250 offers a lot of fuel-economy bang for the buck.
The GLK250 BlueTec uses a 2.1-liter, twin-turbocharged four-cylinder diesel engine codenamed OM651. The twin-turbo setup is designed to increase responsiveness: a large turbo helps provide maximum power, while a smaller one spools up quickly to reduce lag in low-load conditions. The engine computer opens and closes a bypass valve so that the large turbo is only used at higher speeds when more boost is needed. Peak torque of 369 lb-ft is available from just 1600 rpm.
An AdBlue injection system cleans up the exhaust so the GLK meets particulate-emissions requirements in all 50 states. In Europe, this engine gets an automatic stop/start feature to save more fuel, but it’s not installed on the U.S. version. Peter Lückert, director of diesel powertrain development, says stop/start doesn’t help U.S. fuel-economy test results, and American drivers are less interested in the technology than are Europeans. The 2.1-liter diesel is also used here in the Sprinter cargo van and will launch in the E250 BlueTec sedan this September.
Around town, the GLK250 moves off the line just as easily as a comparable SUV with a gasoline turbo-four engine. The accelerator has the precise, progressive tip-in of other Mercedes products, and there is barely any turbo lag. Most drivers will never suffer the wait-wait-wait- power delivery long associated with diesel engines; only if you floor the accelerator from a stop is a second of lethargy evident.
Speed builds in a smooth, deliberate manner, aided by a seven-speed automatic transmission that shifts quickly but gently. Mercedes says the GLK250 takes 7.9 seconds to reach 60 mph, which is 1.5 seconds slower than the gasoline GLK350, and it certainly isn’t athletic or sprightly. But the engine’s calling card is a deep font of torque that makes passing, merging, and powering up hills effortless. Put your foot down to overtake, and you can pick up 20 mph with no drama. The GLK250 never feels underpowered, despite having 102 fewer horsepower than the GLK350.
The one demerit is a persistent diesel clatter that is especially noticeable in low-speed urban driving. A gentle pitter-patter permeates the firewall, and the engine note under acceleration is a gruff, low-pitched thrum. None of the noises are offensive, but they’re a constant reminder that a compression-ignition mill is at work under the hood. It’s a very small price to pay for the efficiency on offer — we saw an indicated 30.4 mpg on our 90-mile test drive.
Business As Usual
Aside from power delivery, the BlueTec model drives just like any other Mercedes SUV. Body motions are well-damped and the GLK250 is controlled and stable, though not particularly sporty, on undulating rural roads. The suspension soaks up bumps so all but the biggest impacts are heard rather than felt. The upright seating position and windshield provide excellent visibility in cut-and-thrust city traffic. A refresh for 2013 brought tauter front and rear fascias, an updated instrument cluster, circular air vents from the SL-Class, and a column shifter that makes room for a storage cubby in the center console. The 2013 GLK250 is handsome inside and out.
Only the BlueTec badging betrays the difference between a GLK250 and a GLK350. The standard equipment list is identical for both versions and includes dual-zone climate control, roof rails, a leather-wrapped steering wheel, a six-speaker sound system, and power front seats; options include a self-park feature, a panoramic sunroof, 20-inch wheels, leather seats, adaptive cruise control, and push-button start. Although there’s a rear-wheel-drive version of the GLK350, the diesel comes only with 4Matic to help Mercedes reduce its number of vehicle variants.
The GLK250 BlueTec is efficient, well-sorted, and just as appealing as the gasoline-powered version. Picking the diesel requires almost no compromises yet brings the twin benefits of lower fuel consumption and a $500 cheaper entry price (compared with the GLK350 4Matic). Customers looking for an economical luxury crossover owe it to themselves to consider the BlueTec. Even so, it will surely not sell in big numbers: diesels account for just six percent of all new Mercedes sales in the U.S.