Mercedes GLS SUV (2013-2019)

The Mercedes GLS (known before its late 2015 facelift as the Mercedes GL) is all about size, space and luxury. It’ll seat seven people in sumptuous comfort with ease, while leaving plenty of room for their luggage, too. In isolation, it’s an impressive vehicle, but in comparison with rivals such as the Range Rover, Volvo XC90 and Audi Q7, it doesn’t come off too well.

A very high list price is one problem, along with the fact the the GLS simply isn’t as good to drive as the Audi or the Volvo. That’s not as much of an obstacle to success in the Middle East and US (where the bulk of GLS sales are expected) as it is in Europe (where even SUV buyers like their cars to be fun to drive).

For most UK buyers, one of the smaller Mercedes GLA, Mercedes GLC or Mercedes GLE is likely to be sufficient – as well as being cheaper to buy and run than the GLS.

There are three versions of the GLS offered in this country: a relatively efficient GLS 350d diesel, the GLS 400 petrol and a high-performance Mercedes-AMG GLS 63 that’s undeniably fast but will cost an absolute fortune to run.

The Mercedes GLS is a big, heavy SUV, so you can’t really expect good fuel-economy figures. The GLS 350d diesel is the most frugal, yet even it only returns 27.7mpg and emits 210g/km of CO2. The GLS 63 AMG, which uses a petrol V8 engine, returns just 17.8mpg and emits 320g/km of CO2. Both cars cost £140 a year to tax, plus a surcharge of £310 in years two to six of ownership because they cost more than £40,000 to buy.

Whether you go for diesel or petrol, Mercedes GLS resale values on the secondhand market aren’t expected to be as strong as rivals such as the Land Rover Discovery and Audi Q7, so there really isn’t much good news on the financial front.

Performance enthusiasts will be pleased with the 5.5-litre V8-powered Mercedes-AMG GLS 63, which can sprint from 0-62mph in a frankly alarming 4.6 seconds thanks to its dizzying 580bhp power output. So despite being seemingly larger than some houses, it’s also quicker than many sports cars.

Sadly, the driving experience falls apart in corners, where the big Mercedes’ huge weight comes into play. You simply can’t throw this car around, but on the plus side, it's extremely quiet and comfortable on the move. The motorway is definitely its natural habitat – not twisty back roads.

That makes the GLS 350d’s 3.0-litre V6 diesel engine much more suited to the model’s character. It’s certainly not as quick as the AMG version, but it’s no slouch, either, with a 255bhp power output ensuring a swift 0-62mph time of 7.8 seconds. It also has lots of the low-down pulling power diesel engines are famed for, so the diesel GLS makes for a superb (albeit pretty expensive) tow car.

Also counting in the diesel’s favour is the fact it comes with Mercedes’ latest nine-speed automatic transmission as standard. The GLS 63 has an older seven-speed gearbox that isn’t quite as smooth and swift through the gears.

If you like cruising serenely down the motorway (or just have to do it on a regular basis), you’ll definitely like the Mercedes GLS. It’s extremely quiet inside, with barely any wind or tyre noise audible. It also comes with air-suspension as standard to iron out bumps and imperfections in the road. However, although the car's large wheels may look great, at low speeds they can make the ride less comfortable than it ought to be - especially if the road is potholed or you've got to negotiate some speed bumps.

An electric power-steering system makes the GLS easy to steer and manouvre despite its quite considerable bulk – although you do need to keep its unwieldy dimensions in mind. The high-up driving position and decent all-round visibility help with this.

This car's been around for a while now and, although it never feels poorly built or like Mercedes has skimped on the quality of the interior materials, it doesn't feel as special as some other luxury cars out there. In fact, it's beginning to seem a little dated. Mercedes has spruced it up slightly recently, but it's still not really on a par with the best of its rivals like the Volvo XC90, Range Rover or Audi Q7. In fact, it doesn't feel as special as in-house rivals like the Mercedes S-Class saloon.

The Mercedes GLS is big – very big. It’s longer than the already pretty unwieldy Range Rover, which pays dividends when it comes to boot space. Even with all seven seats in place, you have a 295-litre luggage capacity to work with, while dropping the third row seats ups that to 680 litres.

The second row can also be folded, freeing up a van-like 2,300 litres for expeditions to the furniture shop. There are tie-down points for securing smaller loads, but disappointingly the lip is quite high.

Access to third-row seats can be tricky in some seven-seaters, but the GLS deals with this by letting you easily flip the middle second-row seat forward so people can climb in. There’s plenty of storage space for odds and ends, too, primarily in the generously sized door bins and glovebox.

The Mercedes GLS hasn't been crash-tested by Euro NCAP, so there's no independent verdict on how it'll fair in the event of a collision. It does feature loads of safety equipment, including lots of airbags, anti-lock brakes and electronic stability control. Lane-departure warning and automatic braking systems also feature, to help prevent you getting in a crash in the first place.

The GLS’ predecessor, the GL, was a fairly reliable car and the latest model’s engines have been tried and tested in many other cars in the Mercedes range. The brand finished 20th in our Driver Power 2018 customer satisfaction survey's manufacturer ranking, so the ownership experience could be improved.