Diesel passenger cars in the U.S. have long suffered from a market that takes two steps forward and one step back, then spends years taking no steps at all. But the 2013 Mercedes-Benz GLK250 BlueTEC 4Matic may just be the tipping point, a vehicle that combines enough refinement and fuel economy to make diesel vehicles a regular consideration for the American car buyer.
The GLK-class slots in as Mercedes-Benz's smaller SUV, coming in about a foot shorter than the M-class. However, the funny thing about SUVs is that the majority only seat five passengers, even when they take up two parking spaces and need a football field to make a u-turn. The GLK-class, with its upright, boxy cabin, offers a spacious interior, although cargo space is down to 23.3 cubic feet, 15 less than that of the M-class.
Mercedes-Benz offers the 2013 GLK-class with a 3.5-liter V-6 gasoline engine or, as the GLK250, with a 2.1-liter four-cylinder diesel engine. Thanks to twin turbos, this little diesel engine generates 200 horsepower and 369 pound-feet of torque.
Don't expect that big torque number to result in four-wheel burnouts with the standard all-wheel-drive system. Not only was there a little turbo lag on take-off, peak torque comes between only 1,600 and 1,800 rpms. When I stomped on the accelerator, the GLK250 set off with reasonable attention, experienced a minor rush from the turbos, then continued its pace, hitting 60 mph from zero in just under 8 seconds, according to Mercedes-Benz's numbers.
That's about one and half seconds slower than the gasoline version GLK350.
And while Mercedes-Benz does a good job of masking the clatter of the diesel engine, it isn't wholly tuned out. From the cabin, I could always here the diesel injectors pounding away as an undertone, more noticeable when idling or at slow speeds, of course. Along with the clatter was a faint odor, not the tarry smell of diesel straight from the pump, but something more like a pool cleaner.
The mild scent was likely due to the exhaust clean-up system, which relies on a urea-based liquid called AdBlue. This exhaust system incorporates an AdBlue tank, which will require refilling about every 10,000 miles.
Here's the why
Given the slower acceleration, extra noise, and added maintenance for the GLK250 over its gasoline counterpart, and that they are priced similarly, you might be wondering why Mercedes-Benz offers the diesel version at all. The GLK250's secret weapon is its fuel economy, which came in at an average of 31 mpg in my week of testing.
The car's EPA numbers registered at 24 mpg city and 33 mpg highway, but when monitoring the trip computer, I saw the average mpg holding around 35 mpg at freeway speeds. During city driving, even in the torturous traffic and up the steep hills of San Francisco, I did not notice a precipitous drop in fuel economy. After putting the GLK250 through its paces, I believe that in most areas it should easily maintain a low 30 mpg average, putting it almost 10 mpg better than its gasoline counterpart.
In many other respects, the GLK250 feels similar to the GLK350. With its fixed suspension, the ride remains firm, and well-engineered components competently deal with potholes and bumps, limiting lean and oscillation. The SUV damped the majority of the shock from hitting big potholes.
The GLK250 uses an electric power steering system, but Mercedes-Benz tuned it for a natural feel. There was no overboosting or electric whirring sounds -- the steering was responsive and the wheel had a comfortable amount of heft. This small SUV also had a decent turning radius, making it easy to maneuver in parking garages.
Along with the all-wheel-drive system, the GLK250 comes standard with a seven-speed automatic transmission. Mercedes-Benz puts paddles behind the steering wheel for manual shift mode, but like wings on an ostrich, these will see little actual use. The GLK250 seems designed for those who want to pay little mind to operating the car. It is by no means sporty, and the transmission did a fine job in automatic mode of applying lower gears when I hit braked on a hill descent.
One quirk of diesel engines is that they run at lower speeds than gasoline engines. The redline in the GLK250 was 5,200rpm. When I did try the paddle shifters for acceleration, I could barely keep up with the necessary gear changes before hitting redline.
Mercedes-Benz includes a button marked E/S on the console, which toggles the GLK250 between economy and sport modes. The switch affects the throttle tuning, but seems like a legacy from the gasoline version -- it made very little difference in feel with the diesel engine. Given the slower acceleration and shorter power curve, there just isn't a lot of room for sport mode. The typical buyer for the GLK250 will likely never bother with sport mode or mess with manual shifting.
While comfortably tooling down the freeway, enjoying the excessive fuel economy, I noticed a couple of ergonomic issues. First of all, while silver fonts on a gray background may look nice in a design studio, the theme sucks for a speedometer. Glare frequently made it impossible to read my speed, especially when I wore sunglasses. An an antidote, the GLK250 sports an LCD in the center of the speedometer, which can bet set to show a digital speed readout.
Blind spots were large enough from the GLK250's driver seat that I found myself craning my neck around any time I planned a lane change. At those moments, I wished this car had come equipped with the optional blind-spot monitor.
Mercedes-Benz offers a big package of driver assistance features for the GLK250, including adaptive cruise control, lane-departure warning, and automatic parallel parking. The model I reviewed only came with a driver fatigue monitor, which looks at factors such as sudden steering inputs to suggest a coffee break, and a back-up camera. The image from the camera was exceptionally crisp, more so than I've seen with other back-up cameras, and it had a layover showing distance and trajectory lines.
Another option included on this GLK250 was the navigation system, which displays on the same seven-inch LCD as the back-up camera. As with all recent Mercedes-Benz models, the GLK250 uses the COMAND interface, with a dial/joystick/pushbutton on the console used to select functions and menu items on the screen. This interface, which has menu strips at the top and bottom of the screen, remains little changed from when it launched in 2005. I found the system easy to learn initially, and it has become second nature after seeing it in many different Mercedes-Benz models over the years.
The interface responds quickly, to menu selections, but Mercedes-Benz should consider modernizing it, as the top menu has become crowded. Voice command complements the system, and covers the basics. It let me enter a street address for a destination, showing good voice comprehension, but I had to enter city, street, and number separately.
While driving the GLK250, what really stood out for me was how well the navigation system does route guidance. For each turn, it recommended moving to the left or right about a mile out, then showed useful turn graphics with lane guidance as the turn came up. The voice prompts even read out the street name.
Of course, route guidance also took into account traffic issues.
The maps themselves look good, and show a few landmark buildings as representative icons, but there is no satellite imagery, as found in Audi and BMW models. The navigation system integrates with the Mercedes-Benz Apps feature, which let me look up businesses on Yelp or Google and set their addresses as destinations.
The integration with Google, Yelp, and Facebook, which I was able to find under a little globe icon on the COMAND top menu bar, looks good. There are big, brand-specific icons for each connected service and the data connection is native to the car, which should mean a seamless online experience.
Unfortunately, the slowness of Mercedes-Benz Apps renders it nearly unusable. Each time I tried to activate it, I had to wait a few minutes while it established a connection. Only then could I select one of the services, and each then took almost as long to load. To use Google, I even had to fill out a terms and licensing form, which was particularly tedious. The services available were good choices, but Mercedes-Benz is far behind the curve in online music. There was no Pandora or any sort of Internet-based radio tuner.
Another facet of Mercedes-Benz connectivity is its mBrace telematics system. A more impressive entrant, mBrace includes a smartphone app that allows remote door unlocking and some vehicle tracking capability.
Despite the lack of online music sources, the stereo comes well-equipped with other digital sources. The navigation system's own internal hard drive serves as an onboard music library, and there is Bluetooth audio streaming, HD radio, and a USB port. There is also a dedicated iOS cable, and despite the GLK250's update for the 2013 model year, it is the old-style 30-pin connector. I attached a 30-pin-to-Lightning adapter, then hooked up an iPhone 5 and the system worked just fine, showing my full music library on the car's screen.
Hopefully Apple's fickle and proprietary attitude towards its connectors will convince automakers to simply allow iOS connectivity through a USB port.
As a pleasant surprise, I drove the GLK250 for a week and assumed that the really nice music reproduction was due to an upgraded Harman Kardon audio system, typical for Mercedes-Benz. Eventually looking at this car's option sheet, I saw that it merely had the base six-speaker stereo system, rather than the available Harman Kardon 12-speaker system.
The base system sounded surprisingly clear, with powerful output throughout the frequencies. It sounded very balanced, not too heavy on bass or bright on treble. I was impressed with how well it brought out the nuances of the music I played through it. I would imagine the aforementioned Harman Kardon upgrade would kick up the quality another notch or two.
Going up against the likes of the BMW X3 and Audi Q5, the 2013 Mercedes-Benz GLK250 BlueTEC 4Matic distinguishes itself by being a very easy driver. Where BMW and Audi may emphasize sport handling, the GLK250 feels designed for comfort and ease. The diesel engine adds a little noise and increased maintenance, but its fuel economy is really outstanding.
The cabin electronics fall a little short compared to the high-end competitors, especially when it comes to connectivity, which suffers mostly from slow activation and poor integration with the vehicle interface. However, I was very impressed with the navigation system's route guidance. And although this particular GLK250 did not come with all the driver-assist features, Mercedes-Benz offers a very compelling package. Given this SUV's big blind spots, any driver would benefit from the blind-spot monitor.
|Model||2013 Mercedes-Benz GLK250 BlueTEC 4Matic|
|Powertrain||Turbocharged 2.1-liter four-cylinder diesel engine, seven-speed automatic transmission|
|EPA fuel economy||24 mpg city/33 mpg highway|
|Observed fuel economy||31 mpg|
|Navigation||Optional hard drive-based system with live traffic|
|Bluetooth phone support||Standard|
|Digital audio sources||Onboard hard drive, Bluetooth streaming, iOS integration, USB drive, auxiliary input, satellite radio, HD radio|
|Audio system||Optional Harman Kardon 510-watt 12-speaker system|
|Driver aids||Optional adaptive cruise control, blind-spot monitor, lane-departure warning, automatic parallel parking, driver-fatigue monitor|
|Price as tested||$50,485|