Mercedes-Benz GLS 350d test drive: Big idea

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This seven-seat Mercedes SUV is supposed to be a high-riding S-Class, hence its GLS badging. But does it really feel that special, or is it just a big GLE masquerading as a high-end luxury vehicle?

Understanding Mercedes’ current five-strong SUV offering is simplicity itself. All of them have ‘GL’ in their name badges, which stands for Geländewagen – German for ‘cross-country vehicle’.

If you know enough about Mercedes and its history, you’ll know that the Geländewagen, despite being nearly 40 years old, still soldiers on today under the G-Class pseudonym; in fact, it’s the only one of Stuttgart’s five SUVs that doesn’t have both G and L in its name.

The G-Class is like a Teutonic Land Rover Defender, an ancient utility vehicle that somehow has evaded the automotive Grim Reaper’s scythe. It’s strikingly ugly, had an original purpose of being a military vehicle and is unmistakably something of an anachronism by 21st century standards.

Doesn’t stop Mercedes, or indeed AMG, slotting a variety of massive power V8s into its ageing, under-developed chassis, though. Nor does it stop people all around the world buying them in their droves.

Anyway, the ‘G-Wagen’ (as it is affectionately known) clearly influences a lot of Mercedes’ thinking and so the other four SUVs in the line-up all wear GL nameplates in honour of the old boy. All that changes from model to model is the letter that supersedes GL, and this is where the simple part comes in.

There’s a small crossover type SUV that shares underpinnings and engines with the A-Class hatchback, so that’s the GLA. There’s a larger machine that’s closely related to the C-Class saloon – which is the GLC. The GLE? Bigger again, and having a lot of commonality with the E-Class executive car.

Mercedes-Benz GLS 350d

Mercedes-Benz GLS 350d

Which brings us onto this GLS, which – despite the ongoing presence of the G-Class, and its sometimes frighteningly silly pricing – is actually the pinnacle of Mercedes’ SUV know-how, an almighty great vehicle with seven seats, all the luxuries on board you’d could conceivably imagine and prices that start at a fairly hefty £69,860.

Due to this supposedly unparalleled premium offering, Mercedes feels confident enough to link this to arguably its most iconic car of all: the S-Class, a technological tour de force that has been leading the way in its market sector for the best part of half a century.

Does the GLS convince as a tower block version of the S-Class, though? Well, that’s what we spent a week with a GLS 350d 4Matic Designo Line model to find out.

In a limited line-up, the GLS is available in just three variants: this 3.0-litre V6 turbodiesel engine with AMG Line trim (from £69,860); alternatively, the same unit but in this Designo Line finish (from £78,095); or with a stonking great 5.5-litre twin-turbo V8 petrol from Mercedes-AMG, the GLS 63 commanding a six-figure starting price of £103,100.

This model, then, seems to offer the best compromise of luxury and cheaper running costs. Although, straight away, we hit a snag. Even though it’s a diesel engine, and a modern diesel engine at that, plonking the 258hp/620Nm motor into something this physically gigantic leads to steep taxation.

It’s in the highest VED bracket of all, meaning an incredible £1,120 of showroom tax and then £515 every year after that, while it incurs the maximum 37 per cent Benefit-in-kind penalty.

Mercedes-Benz GLS 350d

Mercedes-Benz GLS 350d

That’s a direct corollary of its sheer size. At nearly 5.2 metres long, two metres wide and 1.85 metres tall, the four-wheel drive GLS weighs in at a meaty 2,455kg. So despite the fact it has that V6 engine, it’s no faster at top speed (138mph) than the GLC 250d – with a four-cylinder powerplant – that we tested a few months back, and it is slower to 62mph by half a second than that car, taking 7.8 seconds to make the sprint.

You feel every inch of the GLS’s body when you’re behind the wheel. Threading it along a narrow country road becomes one of those exercises where you’re constantly inhaling sharply and then holding your breath when anything larger than a city hatchback comes in the opposite direction.

You also need to plan where you’re going to park the big Merc SUV carefully, because it won’t easily slot into the gaps most people leave between cars in parallel parking, even with its brilliant 360-degree camera system assisting as much as it can.

There are further minor gripes, in that the GLS doesn’t have the beautiful twin 12.3-inch TFT display screens – one in the instrument cluster, one on centre top of the dash – that mark out the other cars in the S-Class family.

Instead, the seven-seat vehicle has the twin-tube analogue set-up in the cluster, with a digital display screen in between, and a screen perched atop the centre stack. In this way, it is more like the GLE below it; and indeed, underneath the body, the stretched chassis is also that of the GLE. It’s looking less and less like a genuine off-roading S-Class by the minute.

Mercedes-Benz GLS 350d

Mercedes-Benz GLS 350d

That’s despite a price tag that comes in at £82,890 with just a couple of options – Driving Assistance Package, £1,695; Off-Road Package, £1,985; Trailer Coupling Package, £950; and black piano lacquer trim, £195 – which makes it a very pricey option compared to, say, a fully-loaded Audi Q7 that might be considered its rival.

We’re well into Range Rover Sport territory here and also not far off full-on Rangie prices. And then we come to the ride on the air suspension.

By and large, it’s superb. Out on dual carriageways, gliding about town, monstering along motorways – you won’t notice the road passing underneath you at all. But then, on more undulating rural back roads, a strange shimmy starts to make itself known.

It’s an unusual sensation, like the body of the GLS is moving laterally while the chassis continues straight on. You notice it most as your head, and the heads of your passengers, bob about a lot when you’re on unclassified country routes doing about 40mph. It’s an odd aberration from the otherwise serene GLS, but – guess what? – it’s something you wouldn’t ever encounter on an S-Class.

If all this sounds like we have a downer on the GLS, though, you couldn’t be more wrong. It might not quite feel as sumptuous and special as an S-Class, but it does feel like one of the very finest SUVs you could hope to drive.

The 3.0-litre Mercedes V6 diesel is an absolute peach of an engine, so strong and muscular in the midrange, and it’s paired to a ‘Plus’ version of Stuttgart’s exceptional nine-speed 9G-Tronic transmission.

For such a giant piece of metal, rubber and leather, the GLS has excellent road-holding abilities and it’s blessed with well-judged brakes and steering that make it a doddle to drive in all conditions; helping ease away the stress of those narrow-roads situations we mentioned earlier.

Where it really aces it, however, is on its practicality. That huge body means a huge cabin. Many seven-seat cars are actually more like 5+2 vehicles, as the rearmost two chairs are so diminutive that only children could contemplate being in them for any length of time.

Mercedes-Benz GLS 350d

Mercedes-Benz GLS 350d

Yet adults could sit in the third row of the GLS in comfort. Not only that, but it even has a semi-useable boot area with all seats in space. And folding them out of the way is elegant in the extreme, as all of the five rear seats electrically fold away at the touch of a button.

With a quintet of chairs in place, the GLS’s boot is cavernous; with all of them folded down, it’s like the back of a Sprinter long-wheelbase van in there.

In the end, we covered 600 miles in the GLS 350d on a touring holiday of East Anglia, spending more than 20 hours behind its lovely, leather-wrapped (and heated) steering wheel during that time. With its climate seats and its radar cruise and its soft-close doors and its automated boot and its head-up display and its charming, easy-going disposition, it made every minute of the whole trip effortless – swallowing family clobber with ease and returning a real-world 30mpg average across the week.

So no, it might not quite feel like an S-Class on stilts, but the GLS is a cut above almost any other vehicle on the roads. There’s an imperious quality to it that’s very similar to that of driving a Range Rover, and yet the Mercedes is the lesser-spotted version of these two cars here in the UK – which meant quite a lot of people, during our time with it, commented favourably on the GLS as it was something a bit different.

That simple Mercedes SUV line-up, then, results in an easy, if slightly obvious conclusion: the best SUV with a three-pointed star on the grille is the biggest one. If you can afford it, the GLS 350d provides a wonderfully exclusive and affluent seven-seat motoring experience that’s truly befitting of a high-end luxury marque. It’s a magnificent, massive machine.

TECH SPEC

  • Model: Mercedes-Benz GLS 350d 4Matic Designo Line
  • Price: GLS from £69,860; 350d Designo Line from £78,095, car as tested £82,920
  • Drivetrain: 3.0-litre twin-turbocharged V6 diesel, nine-speed 9G-Tronic Plus automatic, four-wheel drive
  • Economy: 37.2mpg
  • CO2 emissions: 261g/km – £1,120 VED year one, £515 annually thereafter; 37 per cent benefit in kind
  • Top speed: 138mph
0-62mph: 7.8 seconds
  • Power: 258hp at 3,400rpm
  • Torque: 620Nm at 1,600- to 2,400rpm