Only a G-Class can be better than a G-Class. This is the credo followed by the developers with the Mercedes-Benz G63 AMG 6x6, and they are now stepping up a gear with the G500 4x4². The basic recipe for this overcomer of everything is simple: take the superior all-wheel-drive powertrain including portal axles from the 6x6 - take away one axle - and blend it all with a newly-developed variable chassis and the series-production G-Class body. A large pinch of V8 power with 310 kW (422 hp), a set of 22-inch 325/55 R 22-sized wheels, carbon-fibre body parts and then just gourmet ingredients from the seductive designo Exclusive range for the interior - and the 5-star menu for all off-road enthusiasts is ready.
The 4.0 litre V8 biturbo engine in the G500 4x4² stands out for its sublime power delivery, the targeted lightweight construction, as well as its high efficiency. The newly developed eight-cylinder features twin turbochargers which are not mounted on the outside of the cylinder banks but rather inside the V configuration - what is known as the 'hot inside V'. The advantages lie in the compact engine design, the optimum response and the low exhaust gas emissions. The piezo direct petrol injection used exclusively at Mercedes-Benz is responsible for the mixture formation. The spray-guided combustion process has been enhanced in the third generation to meet all future statutory requirements. In series production, the highly efficient and economical 4.0-litre V8 biturbo engine would meet the Euro 6 emission standard, including the maximum particulate emissions level that will not take effect until 2016.
The V8 crankcase consists of an aluminium alloy and ensures maximum strength with the lowest possible weight. The cylinder walls in NANOSLIDE® technology are twice as hard as conventional cast-iron cylinder liners, minimise the inner friction and thus the fuel required and facilitate maximum mileages. NANOSLIDE® was developed by Daimler starting in the year 2000 and has so far been used successfully and reliably in over 200,000 engines since 2006.
Twin sidepipes on both sides in front of the rear wheels modulate the G-typical sound of the G500 4x4² and master the entire repertoire of potent sports cars - from soft mumbling in neutral through sonorous humming in the partial-load range to emphatic booming when accelerating under full load. A welcome side effect of the sidepipes: there is improved off-road capability, because in the rear area there are none of the usual rear silencers, which could otherwise restrict the angle of departure.
In view of the key data for the chassis and powertrain it seems more than logical that the off-road world starts for the G500 4x4² where other vehicles capitulate. But it is surprising that the new "G" puts in an absolutely convincing performance on the asphalt. Due to the considerably wider track of the portal axles compared with the series-production car (+299 mm), the large 22-inch 325/55 R 22-sized wheels and the adjustable damping with its Sport mode, the enhanced G-Class drives through bends so dynamically that the occupants feel as though they are in a sports car rather than a cross-country vehicle. This also applies to tours on unsurfaced slopes or snow-bound roads, in which case the performance of a high-powered rally car kicks in.
For anyone preferring to use the G500 4x4² off the beaten track, the optional off-road size 37 x 12.5 x 18-inch MT tyres are recommended. Permanent all-wheel drive, an off-road reduction in the transfer case, portal axles and three differentials lockable whilst on the move will not be found on conventional cross-country vehicles. This results in merciless driving dynamics in all conditions. Even the highest sand dunes are stormed by the show car with ease, whilst rocky terrain is scaled like a chamois, and water is driven through without any problems.
The portal axles developed for versatile applications supplement the off-road portfolio of Mercedes-Benz and are the technical highlight of the G500 4x4² show car. As opposed to conventional rigid axles, here the wheels are not at the height of the centre of the axle, instead they are situated much further below on the axle heads due to the portal transmission. Therefore, on the G500 4x4² the ground clearance rises to 450 millimetres and the fording depth - or rather the diving depth - to 1000 millimetres.
At the highest level: the portal axles' tricks
But the portal axle design has yet more decisive advantages which render complex adjustments superfluous: through the unchanged position of the rigid axles in relation to the chassis, the anchorage points of the suspension, the steering connection and the position of the cardan shafts all remain identical. In addition, the reduction in the portal transmissions balances the huge rolling circumferences in both the off-road and the on-road tyres. The gear ratios, speedometer drive and ABS sensor system also remain unchanged. This reduction in the hub drives also has the effect that the drive torque is first set at the wheel and thus the mechanical loads in the entire powertrain, in particular for the drive shafts, are reduced.
Mobile declaration of independence - the chassis
The chassis is fundamentally based on the series-production G model and offers a perfect symbiosis of sporty dynamism and relaxed comfort, both on the road and off it. The new damper adjustment, derived from rally sport, has a decisive effect here. Two spring/damper struts running in parallel are used per wheel. One spring/damper strut works conventionally with set damper characteristics. The second spring strut has electronically controlled adjustable damping, which thus varies the entire damping behaviour depending on the current driving situation. With this set-up, considerable kingpin inclination is possible between the settings SPORT and COMFORT, which the driver can select using a button in the centre console. The switching times between the two modes are record-breakingly low, at 15 milliseconds.
During dynamic cornering the sporty setting performs sterling work, because the significantly tauter connection of the chassis allows higher cornering speeds. If the driver is more in the mood for pleasurable cruising, the COMFORT setting effortlessly dampens all the unevenness in the ground. In extreme situations such as abrupt evasive manoeuvres, the system automatically switches over to the firm setting for the sake of maximum possible handling safety. The comfortable setting also helps during off-road sessions, because the wheels retain better surface contact. Even on heavily contoured off-road terrain, every surface traction possibility can be utilised effectively.
Optimised tyres are available for the G500 4x4², especially for punishing off-road trips: mud/terrain tyres (M/T) in size 37 x 12.5 x 18 inches on special beadlock wheels. Normally the usual wheel/tyre combinations refuse a traction-promoting lowering of the air pressure for journeys on sand, for example, to 0.5 bar. Here 1.0 bar is the lowest limit, because beneath this low pressure the tyres can come off during steering manoeuvres or ingression of sand can infiltrate the sealing surface between the tyre and wheel rim and thus leads to a slow puncture. Not so with the G500 4x4². Here special two-piece 18-inch beadlock wheels are used. With this type of design, during assembly the tyre is pinched in so tightly between the two wheel halves and an inner beadlock ring that it cannot slip off the rim and no sand can enter, even in the case of total loss of air.
Should the chassis ever still come into harsh ground contact in spite of an anticipatory driving style and the excellent ground clearance, the developers have displayed far-sightedness here, too, and integrated a robust, two-piece underguard in stainless steel. These means that the most important assemblies in the front and rear area are well protected against impact and more severe shocks.
Sporty luxury squared
In visual terms the G500 4x4² raises no doubts as to its passion. The voluminous tyres, the huge distance to the ground, the height of nearly 2.25 metres with a width of virtually 2.10 metres and the clear, straight design command respect right from the first glance. Further highlights: the trim with the integral LED light strips above the windscreen and the elaborate partially painted wheel-arch flarings - both in fine carbon fibre - plus the front bumper on the G63 AMG and G 65 AMG models.
The hub of the "G" world is in Graz
The Mercedes-Benz G-Class development department located in Graz is the centre of competence where all things "G" are concerned and is responsible for the development and series support of the legendary cross-country vehicle. Furthermore, Graz in Austria has been the production location for all civilian and commercial G-Class vehicles since 1979. Whether and when the decision on series production of the Mercedes-Benz G500 4x4² will be made depends on the reaction which the near-series show car receives.
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