Mercedes-Benz GLK250 BlueTEC 4MATIC Leads Mid-Size SUVs

The Mercedes-Benz GLK line features the GLK250 BlueTEC 4MATIC – the first diesel-powered entry in the mid-size SUV market and the most powerful four-cylinder diesel engine in the SUV world. With segment-leading fuel economy of 24 miles per gallon in the city and 33 mpg on the highway. Its 2,143 cc direct-injection engine is rated at 200 horsepower and 369 lb-ft of torque.

Its V6-powered sibling, the GLK350, is available for 2015 with a choice of 4MATIC all-wheel drive or real-wheel drive. The GLK350 features a 3.5-liter direct-injection V6 with 302 horsepower and 273 lb.-ft. of torque as well as the innovative ECO start-stop system.

High-Tech Four Cylinder with Balance Shafts

The all-aluminum, in-line four-cylinder engine that powers the GLK250 BlueTEC makes use of four valves per cylinder and dual overhead camshafts with vane-type variable valve timing. To smooth out the inherent vibration of an in-line four-cylinder engine, two Lanchester balance shafts spin at twice crankshaft speed.

Two-Stage Turbo System

To ensure responsive power over a broad speed range, the GLK250 BlueTEC engine features an innovative two-stage turbocharger system that’s comprised of a small high-pressure (HP) turbocharger and a large low-pressure (LP) turbocharger. The two turbochargers are connected in series, with the HP unit located directly at the exhaust manifold and the LP unit downstream.

Exhaust gas flow spins the HP turbine at up to 215,000 revolutions per minute, and the turbine housing has a bypass duct that can be opened or closed by a vacuum-operated wastegate. When the bypass is closed, all the exhaust flows through the HP turbine, allowing high boost pressure to be developed, even at low engine speeds. As engine speed increases, the wastegate opens, and exhaust gas begins to bypass the HP turbine and flow directly to the second LP turbine.

Exhaust gas from the HP turbine and its wastegate reconverge downstream to drive the LP turbine at up to 185,000 revolutions per minute. At intermediate engine speeds, the wastegate is opened wide enough so that the HP turbine ceases to perform any appreciable work. This allows full exhaust gas energy to flow through the downstream LP turbine, which then does all the work.

True Two-Stage Air Pressurization

On the intake side, air from the air filter first flows through the low-pressure compressor, where it is compressed by the LP turbine. The compressed air then flows into the HP turbine, where it’s further compressed for a true two-stage supercharging process.

A Large Intercooler Adds Power

To complement the two-stage turbocharger system, a larger intercooler reduces the temperature of the compressed air by more than 280 F. so that a larger volume of air can enter the combustion chambers. The key benefit of this intelligent, on-demand control is improved cylinder charging and high torque, even at low engine speeds.

What's more, fuel mileage is increased. During normal operation, the advantages of this system can be felt – no turbo lag, fast throttle response, a broad torque curve across the entire engine speed range and noticeably improved performance.

BlueTEC Refinements

Fuel pressure for the BlueTEC direct fuel injection system is 200 bar or 28,400 pounds per square inch, which makes possible even more power and lower exhaust emissions. Higher ignition fuel pressure means the four piezo injectors can be adjusted even more precisely as engine load and speed change. This system places the four-cylinder diesel at the head of the field when it comes to diesel engines for passenger vehicles.

AdBlue Injection

To ensure the GLK250 BlueTEC meets exhaust emission regulations in all 50 states, the BlueTEC system uses AdBlue injection to make the diesel as clean as a state-of-the-art gasoline engine. A water-based urea solution, AdBlue, is carried in its own small tank and metered into the exhaust in minute quantities, so the tank only needs to be refilled during routine scheduled maintenance. When AdBlue is injected into pre-cleaned exhaust gas, ammonia (NH3) is released, converting nitrogen oxides into harmless nitrogen and water in a downstream catalytic converter. Called SCR, for selective catalytic reduction, this process creates the most effective method of exhaust gas after-treatment currently available.

Safety Features

The GLK250 BlueTEC comes with the same innovative Mercedes-Benz safety features as the GLK350, including standard ATTENTION ASSIST and optional DISTRONIC PLUS with PRE-SAFE Brake, Active Blind Spot Assist and Active Lane Keeping Assist. The electrically assisted steering also makes possible a standard STEER CONTROL safety feature and optional Active Parking Assist.

STEER CONTROL

If the GLK begins to oversteer or understeer, the ESP system has an added refinement – it tells the electrically assisted steering to automatically make a slight movement in the direction the driver should turn the wheel to correct the oversteer or understeer. STEER CONTROL doesn’t override the driver, but rather provides a valuable cue.

ATTENTION ASSIST Cautions “Time For A Rest?”

Falling asleep at the wheel causes more than 100,000 accidents a year in the U.S., and the standard ATTENTION ASSIST system can alert drivers to the first signs of drowsiness. A steering sensor is coupled to smart software that uses 70 parameters to establish a unique driver profile during the first 20 minutes of driving.

Between 50 and 112 mph, the system identifies the erratic steering corrections drivers make as they begin to get drowsy and triggers an audible warning, and a “Time for a rest?” message with a coffee cup icon appears in the instrument cluster. ATTENTION ASSIST is a great example of technology that doesn’t need to be expensive to save lives.

Blind Spot Assist

Optional Blind Spot Assist uses dedicated radar sensors to monitor both blind spots behind the vehicle. Whenever a turn signal is activated with a vehicle in the blind spot, the driver gets visual and audible warnings. A separate option, Active Blind Spot Assist incorporates an intervention feature that uses ESP braking to automatically help correct the car’s course if the driver doesn’t heed the initial warning.

Lane Keeping Assist

Another option is Lane Keeping Assist, which makes use of special computer analyzes images from a multi-purpose camera in the windshield to recognize lane markings. This system alerts the driver by simulating rumble strip vibrations in the steering wheel if the car drifts from its lane without the turn signals on.

A separate option, Active Lane Keeping Assist (as well as Active Blind Spot Assist) incorporates an intervention feature, in which ESP braking automatically helps correct the car’s course if the driver doesn’t heed the initial warning.

Adaptive Highbeam Assist

Adaptive Highbeam Assist uses a windshield-mounted camera to control the vertical tilt of both the low- and high-beam headlights. The system is engaged by turning the headlight switch to “Auto” and turning on the high beam setting.

Whenever there are no other vehicles in front, the high beams come on automatically, with the lights increasing gradually rather than suddenly. Since drivers no longer have to think about controlling the high beams, Adaptive Highbeam Assist makes it safer and easier to drive in the dark.

DISTRONIC PLUS with PRE-SAFE® Brake

An optional DISTRONIC PLUS adaptive cruise control system uses radar sensors to help maintain a pre-set following distance behind the vehicle ahead. The system can actually brake the car to a full stop and accelerate it again. DISTRONIC PLUS works at speeds up to 125 mph and can be especially helpful in stop-and-go traffic.

All cars equipped with the optional radar-based DISTRONIC PLUS system reap the benefit of another revolutionary Mercedes-Benz safety feature – PRE-SAFE® Brake. To reduce accident severity, the latest version of PRE-SAFE Brake applies full braking automatically in emergencies.

When PRE-SAFE Brake senses an impending collision with the help of DISTRONIC PLUS, the system sounds three warning tones. About 1.6 seconds before impact is likely, partial braking is automatically initiated, and PRE-SAFE occupant protection measures are activated. If the driver still fails to react, full-power braking is initiated 0.6 seconds before the collision, reducing the impact and effectively acting as an “electronic crumple zone.”

PRE-SAFE Brake builds on the original PRE-SAFE system that Mercedes-Benz launched on the S-Class sedan in 2002. The PRE-SAFE® system automatically tightens the front seat belts during those valuable seconds just before a possible impact, and the front passenger seat move to positions that can provide better protection.

PARKTRONIC

Also optional, PARKTRONIC uses six ultra-sound sensors in the front bumper and four in the rear bumper to detect obstacles in the system’s field of view. The system provides audible warnings and displays the proximity of obstacles using bar graph displays – one on the center dashboard for the front and another for the rear that’s visible in the rear-view mirror.

Active Parking Assist

The electro-mechanical steering assist makes possible Advanced Parking Assist, which works with PARKTRONIC to provide stress-free parallel parking. Below about 20 mph, a “P” icon appears in the dash to show that an electronic parking space search is active. Whenever a parking space is found that’s at least one meter (39.4 inches) longer than the car, an arrow appears next to the “P” icon. When reverse is engaged and the driver confirms Advance Parking Assist is desired, the system initiates automatic steering as the driver controls acceleration and braking at speeds below 7 mph. The system can provide up to five corrections, after which the wheels are straightened.

If the car is parked using Active Parking Assist, the system can also provide a helpful automatic exit feature. When “D” or “R” is engaged, the car asks whether the driver wants automatic exiting. If the driver says “yes,” the system steers automatically to exit the parking space, while the driver controls the accelerator and brake.

Mid-Size Member of the Mercedes-Benz SUV Family

Classed as a mid-size SUV, the GLK is a key member of the successful Mercedes-Benz SUV family that includes the full-size M-Class, which spurred the trend toward more car-like SUVs, as well as the larger GL-Class and the rough-and-tough G-Class. The Mercedes-Benz GLK is just the right size for running errands across town or making a cross-country trip.

The Right Size for Today’s Active Lifestyle

About 10 inches shorter than the M-Class, the GLK is also a few inches shorter than its primary competition – the Acura RDX and Infiniti EX as well as European models such as the BMW X3 and the Land Rover Evoque. At first glance, the GLK appears to be a smaller version of the GL, but a closer look reveals a modern interpretation of the iconic G-Class. In sharp contrast to the relatively soft forms of other similar vehicles, the striking, angular nose of the GLK sets it apart from the competition. From its steeply raked windshield to the integrated rear spoiler on its tightly styled roof section, the bullish shape of the GLK suggests power and agility. At the same time, the GLK is just the right size for today’s active lifestyle, whether it’s parking in town while running errands or making a cross-country trip.

One of the Most Fuel-Efficient Mercedes-Benz Vehicles Ever

Following its 2009 debut in the small sport-utility category, the GLK became one of the most fuel-efficient Mercedes-Benz vehicles ever produced, and it’s also the most agile member of the Mercedes SUV family. Like nearly all Mercedes passenger vehicles, the GLK features four-wheel independent suspension worthy of a sports car. With available 4MATIC full-time four-wheel drive and respectable ground clearance for off-road driving, its integrated running boards, roof rack and skid plates emphasize the versatile SUV character of the GLK.

Agility and Comfort

Smaller and lighter than its well-known SUV siblings, the Mercedes-Benz GLK brings a special combination of agility and comfort to the SUV market. Like nearly all Mercedes-Benz passenger vehicles, the GLK features four-wheel independent suspension worthy of a sports sedan.

Standard Agility Control suspension provides the benefits of both soft and stiff shock absorbers. Each twin-tube shock absorber is fitted with a hydraulic by-pass piston that acts like a very soft shock absorber to effectively dampen road noise and tire vibration. However, over bumpy or uneven roads, the by-pass piston is out of the picture, preserving the outstanding steering and handling response of a stiffer shock absorber.