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Mercedes Benz has revealed details [1997] of its M-class 4WD aka All Activity Vehicle, AAV. The final production form of the car is toned down a little but still has a strong resemblance to the earlier Mercedes Benz AAV show car.
Engine options include new Mercedes Benz alloy V8 and 3.2L V6 engines. The Australian M-class will have a 5-speed automatic transmission. A 2-speed transfer case gives full-time four wheel drive through a centre differential, and has a high-ratio of 1:1 and a low-ratio of 2.64:1. A chain takes drive from the centre differential to the front propeller shaft.
Wheel slip is controlled by an electronic traction control system, ETS. Such systems, as found in the Range Rover, automatically apply the brake on any spinning wheel to redirect torque to those wheels that still have good grip. Mercedes Benz is confident enough in ETS to dispense with diff' locks on all three differentials - which will cause hard offroaders to raise eyebrows. What is certainly true is that ETS is more idiot proof than manual diff' locks and places less strain on drive-line components which can therefore be lighter.
The M-class has a traditional, separate ladder-frame or chassis. The all independent suspension features double wishbones both front and rear, torsion bars being used at the front and coil springs at the rear. The body is rubber mounted to the chassis to reduce the transmission of road noise. Subframes carry the lower suspension wishbones and the upper wishbones attach to the chassis. The suspension control arms are made of forged aluminium and Mercedes Benz claim that unsprung weight is reduced by two thirds over a conventional live axle. All this must make for good handling on-road or on good dirt roads, but it will be interesting to see how much offroad wheel articulation Mercedes has got out of the all-independent design.
Standard safety features on the Mclass include dual air bags, dual front-door side-airbags, four wheel disc brakes, and ABS brakes.
The Mercedes Benz M-class 4WD will go on sale in the USA in late 1997, in the UK in early 1998 and in Australia in "the second half of 1998".
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