Most people would assume that the largest and most expensive Mercedes SUV only sells in modest numbers compared to its smaller siblings. We certainly did, and so were quite surprised when Mercedes told us on the launch of their latest GLS that they had sold over 550,000 examples of the first two generation models since the 2006 debut of the original.
Originally launched under the GL-Class label whilst the company was transitioning from DaimlerChrysler to Daimler AG, the first generation Mercedes SUV flagship (X164) shared its underpinnings with the ML (W164), and came off the same assembly line in Tuscaloosa, Alabama.
The second-generation car (X166) arrived in 2012 and was renamed GLS-Class at facelift time in 2016 to coincide with the revised model nomenclature introduced by Mercedes during that year.
Now the third generation GLS (X167) has arrived, bringing with it softer lines, more space and a raft of technical innovations like E-Active Body Control (E-ABC) suspension and MBUX telematics that deliver an unassailable lead in two critical areas that define comfort and convenience.
The first and second generation cars had a more upright, old school look. While this gave them presence and gravitas it was never going to win them any beauty contests either.
Sitting on a 60mm longer wheelbase and 80mm longer and 22mm wider overall the new third generation GLS (X167) is sleeker, more rounded and dare we say it, friendlier looking than before. Its visual proportions are certainly helped by alloy wheels ranging from 19 to 23-inches, and the 22-inch wheels of our test cars looked spot on in proportion, disguising the sheer size of the GLS until you see it beside another vehicle.
With as much eye appeal as any full size SUV can possibly muster the new GLS makes the Audi Q7 and BMW X7 appear gauche, and it looks like a dolphin compared to the square rigged and much more costly Bentley Bentayga and Rolls-Royce Cullinan.
The spacious cabin with its choice of either six or seven-seat configurations also features the largest Panorama roof in the business that dramatically boosts the sense of space and light no matter which of the three seat rows you occupy.
If you already own a current Mercedes then the state-of-the-art MBUX system that is the core of the infotainment system will be a familiar friend. The GLS also gives you the option of 11.6-inch video screens behind the front seats, and with a total of 11 USB ports on board no portable device will remain uncharged.
With the two rear seat rows folded flat, the 2,400 litre cargo area is cavernous, positively dwarfing the 1,800 litre load carrying volume of the E-Class T-model, the current big estate car class leader. This is also 280 litres more than the BMW X7 can manage.
Open the powered tailgate and folding all seven seats is achieved with one touch of the button on the left side of the load area. Another button returns the seats to the upright position so neither your back nor arm muscles need ever be strained.
While Airmatic air suspension is standard on all GLS models the most impressive option is the E-ABC system that uses a stereo multi-purpose camera at interior mirror level to scan the road ahead. The data gathered is processed in real time by the ECU, which compares it to the maps in its memory, allowing it to be pro-active rather reactive. The system then prepares the suspension for large undulations like speed bumps by raising the ride height in a fraction of a second to ensure that the coming bump is met with maximum suspension travel.
In Curve driving mode the curve tilting function actively leans the GLS into bends like a motorcycle, adopting three stages of anti-roll up to a maximum of three-degrees to preserve the cars horizontal equilibrium in a bend.
Because E-ABC increases cornering speeds by eliminating roll and significantly reducing tyre slip angle to near zero, you could term it a high performance system. On the other hand because roll and lateral g force, the major elements that make occupants uncomfortable in the bends, are effectively neutralised the system also significantly enhances comfort.
The Curve function in its latest form as part of the latest E-ABC system made its debut on the new GLE late last year, and works off the 48-volt electrical system whose instant high current capability provides the muscle. This ties in neatly with the starter/generator EQ Boost system and battery recuperation ability that work together to increase all-round energy efficiency.
The latest E-ABC and Curve driving mode combination are a really big deal as they define the serene way the GLS goes down the road and tackles bends.
Long sweeping curves come and go like they don’t exist, and on the two-lane highway that wends its way around a mountain near Salt Lake City, Utah we could comfortably maintain our straight-line speed round the open bends, blissfully insulated from body roll.
Importantly, the engineers have honed the control algorithms to a fine point. Thus, the artificial feel of the original ABC suspension from two decades ago is gone, the latest system feeling quite natural even though its effect could be described as supernatural. In this respect E-ABC appears to defy Scotty’s famous words, “Ya canna change the laws of physics!”
The good news continues when you leave the blacktop. Although 99.9% of luxury SUVs are hardly ever used anywhere muddier than a polo field, Mercedes always ensures that their SUVs are capable of fully living up to expectation off-road.
While the G-Class, which began its life as a military vehicle still reigns supreme in the rough stuff, the new GLS is not far behind when equipped with the optional Off-Road Engineering Package and the right rubber.
The anti-roll bars that restrict the axle articulation of any vehicle with conventional suspension are not required by the E-ABC system so the four rubber contact patches are able to reach deeper into undulating terrain.
At the same time the Torque On Demand system, reduction gearing and a multi-disc clutch that acts as a central locking differential that are part of the optional Off-Road Engineering Package give the GLS amazing traction on rocks, mud and sand alike.
The transfer case features a low range with a 1:2.93 reduction ratio, which nearly triples the torque available at the wheels. In conjunction with the locking centre differential this maximises traction and gives fine control on very loose surfaces like sand and when crawling over rocks.
Even though the GLS is physically the largest Mercedes-Benz passenger car and is more suited to wide open US roads rather than the comparative confines of European towns, it shows impressive manoeuvrability.
The off-road course featured many tight turns and narrow gullies, and we were surprised that despite the lack off rear wheel steering this huge vehicle showed off an excellent turning circle that got us round some tight turns with just one bite at the wheel.
This is partially thanks to the torque-on-demand system that can go from 0-100% locking at each axle in the blink of an eye. The ability to totally or partially lock or open the electronic diffs according to the situation translates into less understeer and front push when negotiating tight bends at low speeds.
We noted the lack of wheelspin on loose surfaces, the electronics catching a slipping wheel within a revolution or two, while experienced off-roaders will also be impressed by the 29.4° approach, 21.8° break-over and 25.7° departure angles, as well as the 600mm fording depth.
The instructor who accompanied us on the trail explained how a local in a 4x4 pickup tried to follow his GLS test car round. With an old style 50/50 torque distribution via mechanical differentials the pickup soon began to struggle on the tight turns, and the driver threw in the towel about halfway round the course.
Last but not least, the unique ‘rocking’ feature incorporated in the Off-Road Engineering Package helps the vehicle free itself when stuck in sand. This is arguably the toughest off-road situation of all as normally once you are grounded the only solution is to be towed out.
It is quite fascinating to watch this part of the E-ABC repertoire in action, and we are not being entirely tongue-in-cheek in saying that this feature might just clinch a few sales to Rap artists who will no doubt feature it on their videos!
Braking off-road, especially on steep downhill slopes has always been a challenge for ABS systems, which naturally want to unlock the wheels. The Mercedes engineers developed a dedicated off-road ABS system that works up to 40km/h and as we proved on some steep low range first gear descents this gradually and seamlessly transitions from the normal ABS below the target speed.
Back on tarmac roads a quiet cabin is a very important part of the luxury formula. Here all but the smallest 19-inch tyres benefit from a band of acoustic foam on the inside. This tyre technology was first adopted on the Mercedes-Maybach in 2015 and can chop 6dB from rolling noise as perceived by occupants. Double-glazing helps too, as does the class-leading 0.32 drag coefficient since a more slippery vehicle disturbs the air less in the first instance.
Comfort in the spacious rear compartment is sublime, with an excellent secondary ride aided and abetted by the relatively tall tyre sidewalls. At higher speeds the ability of the E-ABC suspension to edit out roll and much of the lateral g-forces out of the cornering equation makes for a truly cossetting travel experience.
A class act chassis that allows the GLS to waft along with such immunity to the road surface needs to be underpinned by an abundance of engine torque. The good news is that all the GLS engines, both petrol and diesel, have this key ingredient.
The numbers for the GLS 580 flagship model are impressive. The M176 3,982cc bi-turbo V8 makes 489hp between 5,500-6,100rpm and 700Nm of torque between 1,600-4,000rpm. Temporarily augmented by an additional 22hp and 250Nm in EQ boost mode, this 2,545kg (EC) SUV can reach 100km/h in 5.3 sec (0-60mph in 5.2 seconds) on the way to its 250km/h (155mph) top speed. Incidentally, all US models are electronically limited to 130mph.
Pushed hard the normally restrained V8 offers up a distant NASCAR grade V8 growl as the slick nine-speed close ratio automatic gearbox smoothly swaps cogs. At the other end of the scale the cylinder shut-off activated in ECO and comfort modes ensures maximum efficiency.
However, the big surprise comes with the GLS 450. On paper the basic 276hp and 500Nm of torque is significantly less than that on offer from big brother V8. Despite a 2,445kg (EC) kerb weight the 2,999cc i6 motor is a sterling performer whose repertoire does not recognise the words ‘slow’ or ‘sluggish’
If anything were astonished at the GLS 450’s snappy throttle response and strong surge of acceleration away from rest. The extra 22hp and 250Nm of torque provided by the starter/generator in EQ Boost mode make a worthwhile contribution, and the 0-100km/h sprint takes a brisk 6.2 sec with top speed pegged at 246km/h.
That strong thrust does not noticeably tail off as the rev counter needle surges round the dial, even at higher speeds. This is in stark contrast to the performance of the bi-turbo six-cylinder version of the BMW X7, whose 340hp i6 bi-turbo lacks starter/generator technology and fields a mere 350Nm of torque, about half that of the GLS 450 in EQ Boost mode.
The US market will only see the petrol engines while the mainstay models in Europe will be the 350d and 400d turbo-diesels, whose outputs are 280hp/600Nm and 330hp/700Nm respectively.
The new Mercedes GLS is a tour de force in the full-size luxury SUV market. It looks good inside and out, offers a versatile, feature-laden cabin, and goes down the road and around corners in a way that should keep it ahead of the pack for some time to come.