If the exterior of the 2015 Mercedes-Benz ML250 pictured here looks nearly identical to the 2014 ML350 it replaces, that’s probably because it is. Comprehensively overhauled for the 2013 model year, the ML’s styling will get updated for next year—when it also adopts the GLE-class nomenclature—but for now the minor change in diesel ML badging is all that’s new outside; it acknowledges the arrival of Benz’s 2.1-liter dual-turbo diesel four under the hood. The same basic diesel engine that provides the Mercedes-Benz E250 sedan and GLK250 crossover with surprising punch and refinement, the 2.1-liter unit is the first four-cylinder oil-burner in decades to find its way into U.S.-market Mercedes passenger vehicles.

2015 Mercedes-Benz ML250 BlueTec 4MATIC

Comparisons are inevitable, so let’s get this out of the way right now: Packing 200 horsepower and 369 lb-ft of torque, the diesel in ML250 trim can’t match the 240-hp and 455-lb-ft ratings of the departed ML350’s turbo-diesel V-6. But losing two cylinders has its benefits, namely a reduction in weight. Registering a still-hefty 5041 pounds on the C/D scales, the ML250 nevertheless shaves 162 pounds off the 5203-pound figure of a 2013 ML350 BlueTec 4MATIC we tested for a recent diesel-SUV comparo.

2015 Mercedes-Benz ML250 BlueTec 4MATIC

Unfortunately, the reduction in weight isn’t enough to offset the loss of muscle. At 8.3 seconds to 60 mph and 16.3 seconds to the quarter-mile mark, the ML250 gives up about a second to the 7.0- and 15.4-second times delivered by the old ML350’s V-6. The torquey four-cylinder provides smart off-the-line acceleration, however, and the sequential turbochargers—a small one provides low-end boost to mitigate lag before handing off to a larger unit at higher engine speeds—do their best to keep momentum building as the seven-speed automatic imperceptibly shuffles though the gears. It’s a reasonable assumption that the suburbanites who make up the target demographic of the ML will never miss the V-6.

2015 Mercedes-Benz ML250 BlueTec 4MATIC

EPA city/highway ratings of 22/29 mpg put the ML250 right in the ballpark with competitors such as the BMW X5 xDrive35d diesel, the Jeep Grand Cherokee EcoDiesel 4×4, and the Volkswagen Touareg TDI. In our hands, the ML250 recorded 24 mpg in combined driving, an identical number to the one we measured with the ML350 V-6; we were hoping for at least a modest improvement in efficiency, given the subtraction of two cylinders and 162 pounds. What the numbers can’t communicate, however, is the 2.1-liter diesel’s willing and amicable nature. Smooth and quiet at idle (for a diesel), it has a polished quality that makes the four-cylinder compression-ignition unit in our long-term BMW 328d xDrive Sports Wagon sound a bit loutish in comparison.

2015 Mercedes-Benz ML250 BlueTec 4MATIC

Read More Via: Car and Driver

It should come as no surprise that the S250 CDI BlueEFFICIENCY and the ML250 BlueTEC 4Matic are among the most environmentally friendly vehicles in their class. Both vehicles are powered by a four-cylinder diesel unit with direct injection and turbocharging. The engine has a displacement of 2143 cubic centimetres, from which it delivers an output of 150 kW (204 hp), placing a powerful torque of 500 newton metres at the driver’s disposal.

The S 250 CDI BlueEFFICIENCY, which is in the luxury class, uses the four-cylinder diesel to accelerate from 0 to 100 km/h (62mph) in 8.2 seconds, while the ML 250 BlueTEC 4MATIC, in the SUV category, takes 9.0 seconds to complete the 0-100 km/h sprint.

But, even with their sporty performances, both of the models are easy on fuel. The S 250 CDI BlueEFFICIENCY consumes 5.7 l/100 km combined (which corresponds to CO2 emissions of 149 g/km combined). The ML 250 BlueTEC 4MATIC consumes 6.0 litres over 100 kilometres, with CO2 emissions of 158 g/km (both figures combined).

Recently, the “ÖkoTrend” institute declared the S 250 CDI BlueEFFICIENCY and the ML 250 BlueTEC 4MATIC to be not just among the best in their class but the best in terms of being the most environmentally friendly cars in their class.

Since 1997 the ÖkoTrend institute has been publishing an environmental ranking for cars on an annual basis. In order to reach a conclusion the institute evaluates the environmental compatibility of several tens of thousands of data relating to around a thousand car models in twelve categories. This stringent assessment includes information on consumption, pollutant emissions, manufacturing, logistics, recycling and the manufacturers’ environmental systems.

The above reseach led to the “AUTO TEST WINNERS in GREEN!” awards from the specialist publication AUTO TEST to go to the Mercedes S 250 CDI BlueEFFICIENCY and the ML 250 BlueTEC 4MATIC.

BlueTEC diesel units and the new generation of BlueDIRECT direct-injection petrol engines form the basis for the excellent economy and outstanding life cycle assessment of the new M-Class. In this respect, downsizing takes centre stage as far as the diesel models are concerned:

• In the ML 250 BlueTEC 4MATIC, the 3.0-litre V6 of the previous model is replaced by the thrifty four-cylinder EU6-standard unit already familiar from, for instance, the S-Class.

• The ML 350 BlueTEC 4MATIC features an extensively revamped 3.0-litre V6, which also betters the EU6 standard and offers far better performance coupled with a substantial reduction in fuel consumption. Thanks to state-of-the-art AdBlue® emission control technology both diesel models comfortably meet the EU6 standard slated for introduction in 2014.

Data comparison with corresponding predecessor model:

State-of-the-art engine technology from the inventor of the diesel passenger car

The 2.2-litre CDI engine turns the ML 250 BlueTEC 4MATIC into the most economical SUV in its class. With NEDC fuel consumption of 6.0 l/100 km, the model even outperforms any hybrid model currently offered by the competition. Despite the low fuel consumption figures, this M-Class model boasts maximum torque of 500 Nm at 1600 rpm and rated output of 150 kW (204 hp) with outstanding performance: the M-Class accelerates from 0 to 100 km/h in 9.0 seconds before going on to a top speed of 210 km/h.

Two-stage turbocharging produces high torque even at low engine speeds. The compressor package – already fitted in the compact SUV GLK 250 CDI 4MATIC – made up of a small high pressure (HP) and a large low pressure (LP) turbocharger contributes decisively to the high output on a par with the 6 cylinder unit in the predecessor model ML 300 CDI BlueEFFICIENCY 4MATIC. The two turbochargers are connected in series, and each has a turbine and a compressor driven by this turbine. The HP turbine is located directly at the exhaust manifold and initially allows exhaust gas to flow through it; it then rotates at up to 215,000 revolutions per minute. The HP turbine housing features an integral bypass duct, which can be opened or closed by means of a charge-pressure control flap. If the flap is closed, the whole exhaust stream flows through the HP turbine, so that the exhaust-gas energy is available solely for the HP turbine drive. This means that the optimum charge pressure can be built up at low engine revs.

The two compressors are likewise connected in series, and are in addition connected to a bypass duct. The combustion air from the air filter first flows through the low-pressure compressor, where it is compressed as a function of the LP turbine’s output. This pre-compressed air then passes into the high-pressure compressor, which is coupled to the HP turbine, where it undergoes further compression. The result is a genuine two-stage turbocharging process. The major advantage of this sophisticated, demand-related control of the combustion air supply using two turbochargers is improved cylinder charging, and therefore high torque even at low engine speeds. Fuel consumption is also reduced. When the car is driven, this concept makes itself felt by harmonious driving characteristics with no turbo-lag, a favourable torque curve across the entire engine speed range, instant responsiveness and excellent performance.

The V6 diesel engine in the ML 350 BlueTEC 4MATIC guarantees effortlessly superior traction. It develops 190 kW (258 hp) and impressive torque of 620 Nm. Despite its extraordinary performance this version boasts combined NEDC fuel consumption of 6.8 litres of diesel per 100 kilometres. The highly efficient V6 diesel unit delivers effortlessly superior performance: the ML 350 BlueTEC 4MATIC accelerates from standstill to 100 km/h in 7.4 seconds before moving on to a top speed of 224 km/h. While delivering performance on a par with the predecessor model, the ML 450 CDI 4MATIC with V8 diesel engine, the new unit, however, boasts 36 percent lower fuel consumption.

Just like the ML 250 BlueTEC 4MATIC, the ML 350 BlueTEC 4MATIC also ranks among the world’s cleanest diesel models: BlueTEC is a technology developed by Mercedes-Benz to reduce emissions from diesel vehicles, especially nitrogen oxides. AdBlue®, an aqueous urea solution is injected into the exhaust gas stream as part of this process, releasing ammonia, which reduces up to 80 percent of the nitrogen oxides into harmless nitrogen and water in the downstream SCR (Selective Catalytic Reduction) catalytic converter. Upshot: both models already comply with the EU6 exhaust emissions standard due to be implemented in 2014. The AdBlue® tank is located under the luggage compartment floor to protect it in the event of a crash, has a capacity of 25.7 litres and is topped up every 25,000 kilometres at the regular service intervals. The filler opening is located behind the side fuel filler flap alongside the tank filler neck and is marked clearly with a luminous blue cap. This configuration allows the ML driver to top up the tank easily if they take full advantage of the off-road capabilities of the M-Class and are unable to find a service station off the beaten track. AdBlue® is available as a refill container from any Mercedes-Benz dealership; the instrument cluster provides a timely indication of the need to top up the tank.

Latest-generation BlueDIRECT direct-injection engine for the ML 350 4MATIC BlueEFFICIENCY

The ML 350 4MATIC BlueEFFICIENCY petrol-engined model features the groundbreaking technology of the new generation of V engines from Mercedes-Benz. At the heart of the BlueDIRECT technology package lies the enhanced third-generation spray-guided direct petrol engine with piezo-electric injectors. In combination with multi-spark ignition, this technology offers further possibilities for fuel savings.

The V6 engine in the ML 350 4MATIC BlueEFFICIENCY utilises a new stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology (“homogeneous stratified mode”). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.

The third-generation direct-injection system also features rapid multi-spark ignition (MSI). How it works: following the first spark discharge and a brief combustion period, the coil is rapidly recharged and a further spark is discharged. The MSI system enables up to four sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition. Controlling this rapid multi-spark ignition enables both the time lapse before the next spark and the combustion duration for the relevant operating point to be optimally adjusted. This provides scope for optimising the centre of combustion and improving residual gas compatibility, especially during stratified charge operation.

The ultra-modern 3.5-litre V6 unit has been designed as a naturally aspirated engine. As a major distinction from the preceding engine in the ML 350 4MATIC, the V-angle between the cylinder banks has been reduced from 90 degrees to 60 degrees. This has enabled the balancer shaft compensating primary vibrations to be omitted. As a result the driver notices an outstanding level of comfort. The design highlights of the 3.5-litre V6 include a completely new air intake and exhaust system in conjunction with a variable resonance intake manifold and optimised inflow and outflow. Result: with the same displacement, the output compared with the previous 200 kW (272 hp) model is increased by 12.5 percent to 225 kW (306 hp), while maximum torque has increased by 5.7 percent to 370 Nm (predecessor: 350 Nm) and now is available over a broader engine speed range from 3500 to 5250 rpm. In parallel with this substantial increase in power, Mercedes engineers have achieved an equally impressive reduction in fuel consumption. The predecessor’s NEDC fuel consumption has been reduced by 25 percent. The new V6 petrol engine in the ML 350 4MATIC BlueEFFICIENCY consumes 8.5 litres per 100 kilometres, making it the most economical petrol model in its class. The model combines excellent consumption figures with dynamic performance, accelerating from standstill to 100 km/h in 7.6 seconds, and with a top speed of 240 km/h.

Data for comparison:

The third generation of the M-Class sets new benchmarks in the SUV segment with its cutting-edge automotive technology. The new M-Class from Mercedes boasts optimum energy efficiency, leading standards of passive safety and unmatched ride comfort combined with superior driving dynamics. In addition, the SUV has a completely revamped interior design offering excellent ergonomics among its key strengths.

The low fuel consumption and exemplary emissions figures make impressive reading – on average, the entire model range burns 25 percent less fuel than the predecessor. Never before has Mercedes-Benz succeeded in cutting fuel consumption by such a huge margin with an SUV model change. An ultramodern engine line-up, a class-beating Cd value of 0.32, extensive BlueEFFICIENCY measures, as well as new development tools such as the “energy-transparent vehicle” all play their part in delivering the good energy efficiency figures. The ML 250 BlueTEC 4MATIC is particularly outstanding in this respect: it is 28 percent more economical than its predecessor, consumes just 6.0 l per 100 km on the NEDC driving cycle (158 g CO2/km) and can cover as much as 1500 kilometres on a single tank of fuel.

In line with the Mercedes-Benz brand philosophy, the new M-Class represents the embodiment of the Mercedes-Benz holistic safety concept of Real Life Safety, which is derived from what happens in a real accident situation. In combination with the front and rear deformation zones, the high-strength passenger cell of the M-Class provides a highly effective foundation for the occupant protection systems. Both active safety and driver-fitness safety in the new M-Class are further improved by assistance systems that will already be familiar, primarily from the S-Class and E-Class.

All models in the new M-Class range offer excellent comfort and dynamic handling as standard – both on the road and away from the tarmac. Besides the steel suspension with selective damping, there are also some new chassis developments and innovative dynamic handling control systems available, which are designed to make driving the new premium SUV an even more effortlessly superior experience. These include the AIRMATIC air suspension with Adaptive Damping System (ADS), the ACTIVE CURVE SYSTEM for active roll stabilisation and the ON&OFFROAD package with six driving modes. A comprehensive package of measures has also been included to ensure that the M-Class is at the forefront of its segment for acoustic and vibration comfort too.

The third generation of the highly coveted Mercedes-Benz M-Class SUV combines the best of both worlds, boasting a strong off-road heritage at the same time as making its passengers feel as if they are travelling in a luxury premium saloon. Ground aluminium or exquisite woods as well as the finely detailed switches and trim highlights blend with electrifying surfaces and powerful, harmonious lines to create a high-class interior ambience and a tremendous sense of wellbeing for both the driver and passengers.