This uses the ABS braking system's components to automatically apply the brake on any spinning wheel, thus directing torque to those wheels that still have grip. The only signs to the driver are a warning light on the instrument console and perhaps some noise from the brakes. Low-ratio gears in the transfer case can be engaged at the press of a button when the automatic transmission is in neutral. This is definitely the simplest of all four wheel drive systems to operate. The main benefits of low-ratio are to increase engine breaking on steep descents and to reduce the load on the transmission on steep, rough climbs.
Automatic transmission makes most ascents easy in high or low-ratio.
The above points do not indicate that the M-class is an offroad wimp. The ML320 could also be said to complement the Jeep Grand Cherokee nicely. The seats are brilliant, really very comfortable indeed. The three rear seats are almost as comfortable and have excellent leg room, loads of it. They can be folded down individually or together in various combinations.