Lovable luxury leviathan Mercedes-Benz GLS improves safety tech

I'm carving my way along winding, narrow ribbons of road through the Austrian Alps. It's cold, the pavement is damp with occasional dustings of snow, and oncoming semi trucks are periodically wandering into my lane. Driving something small and nimble with winter tires would be fun in these conditions and prevent me from worrying about having a side mirror smashed off, but I'm not in anything like that. Instead, I'm wheeling a 2017 Mercedes-Benz GLS 400 4Matic. With my ride featuring seating for seven, weighing in at nearly 5,400 pounds and having an inherently high center of gravity, the GLS isn't the sort of on-road athlete really capable of putting these entertaining roads to their best use.

Even so, the big crossover SUV formerly known as GL holds its own in these circumstances. It never feels clumsy or totally out of its element on roads better suited for much smaller things like a Mazda MX-5 Miata or Porsche Cayman. I'm not saying you should go out and buy a GLS for autocrossing, but around all sorts of corners and tight turns, it goes about its business far better than any two-and-a-half-ton hunk of rolling steel has a right to. It drives smaller than it is. Credit its light, but responsive steering that makes it easy to accurately place the GLS where you want it, and a revised air suspension that keeps body motions tidy.

I'm running the GLS 400 with its Dynamic Select system in Sport mode, giving me tighter steering and firmed-up suspension programming that aims to minimize lateral movement. It'd be foolish to expect all body roll to be ironed out, but what's there is acceptable. Ride quality is predictably a touch firmer in Sport compared to Comfort (which is magic-carpet-ride smooth), and this mode yields more-than-respectable handling. Switching between the different Dynamic Select settings is simple enough, requiring just a twist on a center-console knob. In addition to Comfort and Sport, there's Individual for tailoring the vehicle's various drive systems to your liking, Slippery (more on that later) and Off-Road.

The 2017 Mercedes-Benz GLS' 4Matic all-wheel drive proved more than capable of tackling slick conditions.

Jon Wong/CNET

Keep in mind I'm driving the base Euro-spec GLS. It doesn't have the optional active roll stabilization system that promises to curb roll even further, nor is it the AMG model that has all sorts of goodies from Benz's in-house Affalterbach speed shop. The equivalent version of my test vehicle will be called GLS450 (no space) in North America, and it'll be the volume model that Benz estimates will account for 70 percent of sales. Translation? It needs be good. Really good.

Fortunately, it is. The turbocharged V-6 in the GLS450 carries over with 362 horsepower (29 horsepower more than the GLS 400 due to different tuning) and 369 pound-feet of torque available from just 1,600 rpm. With peak twist available so low in the rev range, the less powerful GLS 400 never feels underpowered off the line or up steep inclines. Of course, even with the additional oomph in the US-spec GLS450, things may be different when toting around five or six adults and a cargo bay full of gear, but on this day, with just two aboard, the big Benz feels plenty stout.

For those looking for more engine choices, Mercedes has you covered. A 3-liter diesel V-6 with 255 horsepower and a hearty 457 pound-feet of torque powers the GLS350d, and an updated 4.6-liter turbo V-8 with 449 horsepower (20 more than its predecessor) and 516 pound-feet of torque is found in the GLS550. At the top sits the Mercedes-AMG GLS63, a model that sees output jump by 27 horsepower to 577 from its turbocharged 5.5-liter V-8.

I also scored time behind the wheel of a Euro-spec GLS 500 with 455 horsepower, and put the extra grunt to good use climbing up some treacherous roads leading to the top of a mountain. The changing road conditions as I ascended put the 4Matic all-wheel-drive components and the Dynamic Select system's Slippery mode to the test. On surfaces ranging from black ice to packed snow, the GLS 500 was surefooted on the way up and the way back down. No doubt, the Continental winter tires on my tester helped, but 4Matic optimally routing power smoothly in Slippery mode was also pivotal for getting the GLS up the steep, snow-covered inclines with almost no tail wagging. The confidence the SUV provided in these conditions prevented any thoughts of sliding off the edge of the road, falling to certain doom. For comparison's sake, I temporarily punched up Sport mode, only to find traction control aggressively cutting in at the first sign of wheel spin, a condition making for much jitterier climbs.

The 2017 Mercedes-Benz GLS handles remarkably well for a vehicle its size.

Jon Wong/CNET

Mechanically, the biggest news for the GLS is its new nine-speed automatic transmission, which replaces the previous seven-speed unit on all models except the AMG, which continues with the seven-speed. The new gearbox does a fine job ripping off seamless gear changes when left in full-auto mode, and impresses with its response to manual shift commands. In particular, upshifts are nearly instant, and downshifts are also quite snappy. With a couple of extra gears to work with, expect the GLS450's fuel economy to improve some over the 17 mpg city and 21 mpg highway EPA rating on the 2016 model.

Being a mid-life refresh, visual changes to the GLS aren't terribly substantial. Up front, there's a wider, steeper grille, power dome hood, and restyled headlamps with available LED innards. In back, there are matching revised LED lights and a new bumper. Even though the changes are minimal, the GLS's nose looks more defined and sharply chiseled than the GL's softer, more rounded-off appearance.

Interior updates are on the light side, too, with a redesigned instrument panel and center media screen, a new three-spoke steering wheel and a revised center console. Major changes weren't necessary, though, as the GLS' cabin remains a very comfortable setting, with quality materials, attractive wrapped surfaces, firm and supportive bucket seats, intuitive infotainment controls, and good isolation from road and wind noise.

A new three-spoke wheel, instrument panel, central screen and center console are among the big cabin updates.

Jon Wong/CNET

Speaking of infotainment, Apple CarPlay will be available when the GLS goes on sale in the US at the end of March, but Android Auto fans will have to wait a little longer. A Mercedes spokesman confirms that the tech is coming, but there isn't yet a clear timeframe for its arrival. Other available features include the latest iteration of Benz's Comand infotainment system, complete with an 8-inch display and center console touchpad controller. For even more connectivity, an optional mbrace Connect package offers features like remote vehicle start, remote locking/unlocking, and roadside assistance through an Apple iPhone or Android app.

Safety features including collision warning with auto brake, crosswind assist and attention assist are standard, while adaptive cruise control with steering assist, automatic emergency braking with pedestrian detection, blind spot monitoring and active lane-keep assist are options on the GLS.

Pricing for the 2017 GLS hasn't been announced, but when it arrives in dealers in late March, expect it start around $67,000 for the GLS450, while upgrading to the GLS550 will bump things up to around $92,000. The GL350 diesel will likely remain the bargain of the lineup, with a base price around $65,000, and the mighty Mercedes-AMG GLS63 should ring in at roughly $122,000. In the UK, only the diesel and AMG will be offered, with a base price of £67,940 and £100,560, respectively. Australia will get the diesel, GLS 500 and AMG, but pricing information has yet to be made available.

Even with only minor updates and an additional letter in its name to signify that it's the S-Class of Mercedes' crossover lineup, Benz has done enough to keep the GLS competitive in a class that doesn't have many challengers. Fellow German luxury brands don't offer opponents that stack up all that closely -- ostensible three-row rivals like the BMW X5 and Audi Q7 are actually quite a bit smaller. Models like the Cadillac Escalade and Lincoln Navigator match the GLS on size, but are well short on refinement. And the Infiniti QX80 while cushy, doesn't possess the handling chops of the Mercedes, nor does the lumbering and aging Lexus LX.

Sure, one could complain that Mercedes could have done more to improve the GLS, but the new nine-speed transmission and small revisions inside and out are indeed improvements to an already excellent luxury hauler of people and stuff. Families in the United States certainly seem to like this vehicle, what with the market accounting for 60 percent of model sales worldwide. In the end, I really can't blame Mercedes for not wanting to risk making too many tweaks to an already winning formula of utility, all-weather capability and comfort.

Editors' note: CNET accepts multiday vehicle loans from manufacturers in order to provide scored editorial reviews. All scored vehicle reviews are completed on our turf and on our terms. However, for this feature, travel costs were covered by the manufacturer. This is common in the auto industry, as it's far more economical to ship journalists to cars than to ship cars to journalists. The judgments and opinions of CNET's editorial team are our own and we do not accept paid editorial content.

Discuss 2017 Mercedes-Benz GLS