Like the ML, the GL gets 4MATIC permanent all-wheel drive system. It features front, rear and centre diffs working with Mercedes-Benz’s 4-ETS electronic traction control. Normally the torque distribution is 50-50 front-to-rear. But if the system senses a wheel slipping it can re-direct the torque front to rear and side to side to the wheel, or wheels, with grip.
If serious mud plugging is in your future, there’s a pukka off-road package available. It includes a modified AIRMATIC system that raises the body higher to give up to 307mm of ground clearance added to the ability to splash through water 600mm deep.
On more demanding roads the GL is as good as, but little better than its off-road-biased rivals – which means it’s more cumbersome than a Q7, Cayenne or X5. It’s also noticeably poorer than the five-seat ML. It might get adjustable dampers with three modes, but none is truly satisfying for brisk road driving.
In Automatic and Comfort modes it lacks proper body control. Movements are more tightly checked in Sport mode, but the ride becomes a touch lumpy. It's not dangerous under braking, and we’ve no qualms about stopping power, but the brakes suffered fade after only a few high-speed stops.
Its lengthy, 3075mm wheelbase limits agility, but axle articulation is first rate, and even without the differentials locked the electronics distribute power so it can drive along with two wheels airborne. Off road, it’s a struggle to exhaust the GL’s ability.
At its highest, the GL’s fording depth is 600mm and ground clearance 307mm. It has 33deg and 27deg approach and departure angles respectively, and will tip over only after listing 35deg. There’s a full-length skid plate underneath, lockable differentials, a hill descent system and a low-range set of gears. In short, it’s as equipped as any big SUV for off-roading.