|2012MY M-Class. Click to enlarge.|
Mercedes- Benz will introduce the all-new 2012MY M-Class SUV into the US market in September 2011 with two models: ML350 4MATIC and ML350 BlueTEC.
The third generation of the Mercedes-Benz M-Class SUV features a completely reworked 3.0L diesel for the ML350 BlueTEC model that which meets emissions standards in all 50 states and delivers improved performance, yet with considerably reduced fuel consumption.
The efficiency improvements have been achieved mainly through the use of the TWAS (twinwire-arc spraying) technology for reducing internal friction in the engine—in use since 2005 in AMG’s successful high-performance engines. The positive results at AMG led Mercedes-Benz to adapt this cylinder wall coating technology for use in the V6 diesel engine as well.
At the same time, the weight has been reduced by 9.5 lbs., as there is no longer any need for the grey cast iron cylinder liners that, until now, had to be pressed into the engine block. With these measures alone, fuel consumption could be reduced by around 3%.
|Comparison of the ML350 BlueTEC diesels|
|ML350 BlueTEC 4MATIC (estimated)||ML350 BlueTEC 4MATIC (Predecessor)|
|Rated output hp/kW||240/179||210/157|
|Max torque lb-ft/N·m||455/617||400/542|
|US fuel economy city/hwy||20/25 (est.)||18/25|
The ML350 4MATIC gasoline-engine model offers a new BlueDIRECT engine generation. The direct gasoline injection system with spray-guided combustion and new piezo injectors offers an injection pressure of 2,900 psi, together with fast, multi-spark ignition and a new combustion process.
|Comparison of the ML350 gasoline engines|
|ML350 4MATIC (estimated)||ML350 4MATIC (Predecessor)|
|Rated output hp/kW||302/225||268/200|
|Max torque lb-ft/N·m||273/370||258/350|
|US fuel economy city/hwy||17/22 (est.)||15/20|
The fuel economy is supported by a package of BlueEFFICIENCY measures including the new seven-speed automatic transmission with a more fuel-efficient torque converter, friction-optimized bearings and a transmission oil thermal management system. Low-friction axle drives and electromechanical steering also contribute in reducing fuel consumption.
The optimized belt drive system with decoupler, together with on-demand control of all auxiliary components and pumps, also help to reduce the energy requirements of the 2012 M-Class. The oil and water pumps in the engine, as well as the fuel pump in the rear of the vehicle, are only activated according to actual need. The same control logic is used in the air conditioning systems. In these, the coolant compressor only runs when necessary. A key factor in the diesel engines is also the optimization of the flow and backpressure in the exhaust system with its SCR (Selective Catalytic Reduction) emission control technology.
A consistent use of lightweight construction techniques has enabled the development engineers to keep the weight of the M-Class on a par with that of its predecessor, despite more equipment. The hood and fenders, for example, are made out of light and yet very strong aluminum alloys, while the cross member for the instrument panel is made of magnesium.
The “energy-transparent vehicle” development tool, created in-house by Mercedes-Benz, was used for the first time as part of the 2012 M-Class development process. The opportunities presented by this method, which detects optimization possibilities right down to even the most minute component, will be exploited on all new models in the future. An exact and meticulous examination of the flow of energy throughout the vehicle (tank-to-wheel) helps the development engineers to optimize every single assembly that has an impact on fuel consumption, right down to individual wheel bearings.
Simulations undertaken with the digital prototype, along with final touches added in the wind tunnel, resulted in an optimized flow of air around the vehicle. The key factor determining the low wind resistance is the aerodynamic efficiency of the basic body shell, including the optimized design of the front bumper, A-pillars and the roof spoiler, plus numerous other detailed improvements. These include:
- Sealing around the radiator section
- Sealed joints between the hood and the headlamps
- Front wheel spoilers
- Air outlets in the front wheel well liners
- Redesigned exterior mirror housings
- Optimized roof spoiler
- Underfloor and engine compartment paneling
- Aerodynamically optimized light-alloy wheels