Parkers overall rating: 4.2 out of 5 4.2

Which Mercedes-Benz GLS engine is best for me?

  • Not the most comprehensive engine range
  • Just diesel at the car’s launch
  • Petrol coming later, plus an AMG

Only one version of the GLS is initially available in the UK. Called the GLS 400 d, it features a stout 3.0-litre diesel that produces 330hp and a whopping 700Nm of torque, channelled to all four wheels via a nine-speed automatic and Mercedes’ 4Matic all-wheel-drive system.

It’s no slouch, despite its size and weight; Mercedes claims that the diesel can propel it from 0-62mph in 6.3 seconds and, where appropriate, that it can hit 148mph. Its economy is a little less impressive, though, with the hefty GLS recording a claimed average of 35.8mpg and CO2 emissions of 208g/km.

Coming later is a GLS 450 petrol, using a 3.0-litre petrol unit with 367hp and 500Nm of torque, and it’s a very smooth performer with plenty of performance. It comes with a 48-volt mild-hybrid system with what Mercedes calls EQ Boost, enabling sharper bursts of acceleration when you need it. This car will manage 0-62mph in 5.7 seconds.

It even sounds pleasant with a silky smooth power delivery and good responses. The only issue will be running costs. Despite being very pleasant and refined, the diesel will be most buyers’ preference due to the better fuel economy.

There will also be an AMG version called the Mercedes-AMG GLS 63, but we don’t have any performance figures on this just yet. Expect the firm’s 4.0-litre V8 to feature, though.

How does the Mercedes-Benz GLS drive?

  • Focus on comfort over anything else
  • Which it excels at from what we’ve experienced
  • Clever suspension options available

The GLS should prove a relaxing car to drive, nonetheless, thanks to new underpinnings that are designed to boost comfort. It comes with adaptive air suspension as standard, too, which adjusts its characteristics on the fly to suit the road conditions – and also keeps the car level, regardless of load. 

It floats over smooth surfaces and adjusts itself impressively well – even Sport mode offers a decent degree of comfort. Leave the car in Comfort for the majority of the time though, and it’ll be a quiet and relaxing place to be. It can sometimes thud into bigger holes and, with such large wheel sizes available (up to 23 inches), this feeling is heightened, but it’s never uncomfortable.

The GLS even handles quite well for such a large beast. On a twisty road it’s best in Sport mode to keep the large body in control, but when fitted with the e-Active suspension system, there’s a function called Curve to actively tilt the car into a corner to reduce body roll. It takes a little getting used to, but it doesn’t leave you rolling around in the car.

There’s not a huge amount of feedback in the steering wheel, but you wouldn’t really expect there to be. It’s easy to drive the GLS though, which will be far more of a priority than how sporty it feels.

Impressive off-road ability

While it’s unlikely that any GLS will ever venture far off the beaten path, Mercedes has served up an upgrade that boosts the big SUV’s off-road capabilities. It’s called the Off Road package, which costs £1,495, and includes upgrades such as a low-range crawler gear, hill descent control and off-road calibration for the ABS.

Even without this kit fitted, the GLS is more than capable of tackling some tricky terrain thanks to adjustable air suspension.

Two off-road driving modes are available via the Dynamic Select system, adjusting the car’s systems to most effectively make its way over tough surfaces. It’s more than a match for Land Rover’s selection of cars, which is impressive in itself.