by Ian Kuah
The Mercedes GL-Class, renamed GLS during the second-generation model's 2016 facelift, has been a spectacular sales success with over 550,000 units sold worldwide since the original's 2006 debut.
Sharing its platform with the ML-Class (now GLE) mid-size SUV, and rolling off the same production line in Tuscaloosa, Alabama, the all-new third generation GLS has now arrived with the option of six or seven seat configurations at no extra cost.
Where the new GLS really scores is in its perception as a prestigious SUV version of the S-Class. That means it can be executive transport by day, and VIP conveyance for dinner and theater in the evening.
In its first two incarnations the GLS, and indeed the previous generation GLE, did not offer any particular areas of clear superiority over its class rivals from Audi or BMW. Now however, the all-new Mercedes GLS is able to capitalize on the E-Active Body Control (E-ABC) suspension and MBUX telematics introduced on the GLE last year to deliver an unassailable lead in the critical areas that define comfort and convenience.
The previous GLS models had a more upright, old school look. While this provided impressive physical presence and gravitas it was also never going to win them any beauty contests either, even by SUV standards.
Sitting on a 123.4-inch (2.36-inch longer) wheelbase and measuring 3.15-inches longer overall (205 in.) and 0.87-inch wider (84.9 in. with mirrors) the new third generation GLS is sleeker, more rounded and friendlier looking than before. With as much eye appeal as any full size SUV can possibly have it looks like a dolphin compared to the chunky Audi Q7 and BMW X7, whose design ethos is clearly rooted in the school of thought that produced the previous GLS.
The softer lines start with the nose in which the large, imposing grille sits quite happily. In stark contrast with the upright grilles of the Audi and BMW the fact that this massive version of the classic Mercedes sports grille is a horizontal element helps to make the GLS look lower and wider than its rivals.
The flanks show the now familiar minimal sculpting lines that underpin the current Mercedes design philosophy, giving this huge vehicle a seemingly contradictory elegant simplicity. The rear end treatment matches the front in using strong horizontal elements like the full width chrome strip above the slim LED tail lights to visually reduce the height of the tail, giving the GLS a broader, lower stance.
Wheel and tire size is very important in establishing the visual proportions of a vehicle, and here Gorden Wagener's design team have hit the nail on the head. With factory wheel options ranging from 19 to 23-inch, the GLS belies its physical size, and our test cars all wore 22-inch rubber that make it hard to tell how big the car is in isolation, especially from a distance.
The packaging engineers have made full use of the 3.15-inch longer wheelbase to produce a truly spacious cabin with a choice of either six or seven-seat configurations. The comfortable driver's seat gives you a commanding view over the hood. The huge range of seat adjustments allows the driver to lower the seat for a more car-like feel when using the prodigious cornering provided by the E-ABC suspension in Curve mode, and then raise it for maximum visibility when driving off-road.
If you already own a current Mercedes then the state-of-the-art MBUX system will be a familiar friend. The bespoke software suite includes specific off-road information on the MBUX screen, especially if you have specified the Off-Road Engineering Package.
Extensions to the infotainment system are a pair of 11.6-inch video screens behind the front seats and a total of 11 USB ports on board so that no portable device remains uncharged. Meanwhile, an even greater sense of light and space is created by the addition of the largest panorama roof in the business. This dramatically boosts the sense of space and light no matter which of the three seat rows you occupy.
Space in the second seat row in particular has been enhanced, with electric adjustment facilitating 3.9 inches of fore and aft movement to help occupants achieve maximum comfort, with legroom increased by 3.4 inches with this row all the way back.
All six/seven seats benefit from electric adjustment and this extends to the Easy-Entry function that folds and motors the outer seat of the second row forward to allow access to the two third row seats. There should be no complaints from occupants of these heated seats, which were designed to accommodate people up to 6 ft. 3 in.
Folding all seven seats is the work of one touch of a button on the left side of the load area once you have opened the powered tailgate. As another button returns them to the upright position, neither your back nor arm muscles need ever be strained.
Trunk volume is 17.4 cu ft, but with the two rear seat rows folded flat, the 84.76 cu. ft. cargo area becomes truly cavernous. This not only dwarfs the 63.57 cu. ft. load carrying volume of the E-Class wagon but is also 9.9 cu. ft. more than the BMW X7, the GLS's head-on class rival can manage.
Only the bi-turbo gasoline engines will be sold in the US: the V8 GLS 580 and straight-six 6 GLS 450. The mainstay models in Europe will be the 350d and 400d turbo-diesels, whose outputs are 280 hp/443 lb-ft and 330 hp/516 lb-ft respectively.
The engine output numbers for the GLS 580 flagship model are impressive. Despite an already healthy 489 hp between 5,600-6,100 rpm, underpinned by 516 lb-ft of torque from 1,600 to 4,000 rpm, the M176 4.0 liter bi-turbo V8 is further enhanced by an additional 22 hp and 184 lb-ft in EQ boost mode.
The short term electrically enhanced boost mode helps to shove this 5,611-pound monster to 60 mph in just 5.2 seconds on the way to its 155 mph top speed. However, that Vmax is for ROW models, and in the US top speed is electronically pegged at 130 mph.
Towing capacity is a massive 7,700 lb, so hauling the largest Airstream caravan is not a problem, while a new reversing aid camera system helps you maneuver it too.
Pushed hard the normally restrained and silky smooth V8 lets loose a distant NASCAR grade V8 growl as the slick nine-speed close ratio automatic gearbox seamlessly swaps its cogs. At the other end of the scale the cylinder shut-off activated in ECO and comfort modes ensures maximum efficiency. As the GLS is currently undergoing EPA certification its gas mileage numbers are still pending.
The big surprise comes with the GLS 450. On paper the bi-turbo straight-six that powers the entry-level GLS delivers 276 hp from 5,600 to 6,100 rpm along with 369 lb-ft of torque from 1,600 to 4,000 rpm. Once again the extra 22 hp and 184 lb-ft of torque provided by the starter/generator in EQ Boost mode makes a worthwhile contribution to performance with 0-60 mph taking a brisk 5.9 sec, on the way to a top speed of 153 mph other than in the US.
However, these stopwatch numbers cannot describe the pleasingly spritely subjective performance it delivers. Despite the 5,390-lb curb weight it is tasked with hauling this base motor turns out to be a sterling performer whose repertoire does not include the words 'slow' or 'sluggish'.
We were quite astonished at the snappy throttle response, strong surge of acceleration away from rest, and vivid turn of speed the GLS 450 showed on the open road.
The strong thrust does not noticeably tail off as the rev counter needle surges round the dial, even at higher speeds. It has to be said that this is in stark contrast to the lackluster performance of the BMW X7 xDrive 40i, whose 340 hp, 3.0-liter TwinPower Turbo straight-six fields a mere 258 lb-ft of torque; about half that of the GLS 450 in its EQ Boost mode.
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 and gather data that is processed in real time by the ECU. This compares it to the maps in its memory, allowing this pro-active system to prepare for large undulations like speed bumps, raising the ride height in a fraction of a second to ensure that the coming bump is met with maximum suspension travel.
Isolation from mechanical and road surface noise is a very important part of the luxury formula, and here all but the smallest 19-inch tires benefit from a band of acoustic foam on the inside. 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 tire sidewalls. At higher speeds the ability of the E-ABC suspension to edit roll and much of the lateral g-forces out of the cornering equation makes for a truly cossetting travel experience.
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, which helps to preserve the cars horizontal equilibrium in a bend.
As E-Active eliminates roll and significantly reduces tire 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 neutralized the system also significantly enhances comfort.
The 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. In short, where you would normally be holding on to the grab handles for dear life in an SUV being cornered ambitiously, you can be totally relaxed in an E-ABC equipped GLS.
Long sweeping curves come and go like they almost don't exist, and on the two-lane highway that wends its way around a mountain near Salt Lake City, Utah we comfortably maintained our straight-line speed round the curves, blissfully insulated from the cornering forces.
Of course all this is only possible thanks to the 48-volt electrical system whose instant high current capability provides the muscle to work these systems. 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 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 their vehicles are capable of living up to high expectations.
While the G-Class, which began its life as a military vehicle still reigns supreme off-road, the new GLS is not far behind. 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. Experienced off-roaders will be impressed by the 29.4° approach, 21.8° break over and 25.7° departure angles as well as the 23.6-inch fording depth.
The Torque On Demand system, reduction gearing and a multi-disc clutch that acts as a central locking differential that are part and parcel 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 center differential this maximizes 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 so more suited to wide open US roads rather than the comparative confines of European towns, it does not want for maneuverability in the rough stuff.
The off-road course held many tight turns and narrow gullies, and we were surprised that despite lacking rear wheel steering this huge vehicle has an excellent turning circle.
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 resultant front push when negotiating tight bends at low speeds. We also noted the lack of wheel spin on loose surfaces, the electronics catching a slipping wheel within a revolution or two.
Finally, 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.
The new Mercedes GLS is a technical tour de force in the full-size luxury SUV market. Its smooth, classy lines, load carrying ability, towing capacity, and cutting edge driver assistance features give it a tangible aesthetic and technical leg up over its class rivals. Importantly, it goes down the road and around corners with a level of comfort and composure unmatched by any potential rival.
With the Audi Q7 now approaching half-life and the BMW X7 only launched earlier this year it will be a while before the GLS encounters any meaningful resistance.
US market deliveries start at the end of 2019 with the GLS 450 costing $75,200 excluding destination and delivery charges. The price for the GLS 580 is significantly higher, starting at an eye-watering $97,800 before taxes.