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Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive (2021-)

Take the luxurious Mercedes S Class, pump it full of steroids and complete the look with 23-inch AMG alloy wheels and the result is the mighty GLS SUV.

Starting price:
From £75,610 (test car was £93,610 without options)

  • Spacious seven-seater with fully powered seats for easy access
  • Performance is impressive for such a large vehicle
  • Packed with the latest on-board tech
  • Pricey to buy and expensive to run
  • It feels huge on narrow lanes
  • Some rivals are more fun to drive
More On This Car
Take one for a spin or order a brochure
Request a Mercedes-Benz GLS brochure
Request a Mercedes-Benz GLS test drive


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

If you are in the market for a fully loaded seven-seat SUV that boast all the bells and whistles imaginable, plus puts in a very impressive performance, then the GLS could be the answer.

It is the biggest SUV that Mercedes makes and takes 4x4 driving to a truly executive level. There is all the advanced on-board tech you would expect in a Merc and the clever powered seating arrangement is so good you will want to show it off at every opportunity.

A choice of trim levels allows customers to get exactly the model they want and, of course, the price is not for the faint-hearted.


On The Road

Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021


The GLS 400 d 4MATIC features a 3.0-litre, six-cylinder, in-line diesel engine that produces 330hp and 700Nm of torque. It is mated to a 9-speed automatic gearbox and, despite weighing in at almost 2.5 tonnes, the GLS can power its way from 0-62mph in just 6.3 seconds and onto a top speed of 148mph.

Built in the USA, the latest GLS has had quite a growth spurt so is bigger than ever. But thankfully the added bulk hasn’t had an impact on the car’s performance.

It is brutally quick for such a large unit and the acceleration through the gears is rapid with steering wheel mounted paddles for added driver engagement.

The GLS cruises effortlessly at 70mph on motorways, where it almost glides along, but is also accomplished through the twisting country roads too. Narrower lanes can test your nerves a little as the GLS stretches 2.15 metres across, but with a whole host of sensors, a 360-degree camera and parking aids, the car is deceptively agile in built up areas.

Drive modes called Eco, Comfort, Sport and Individual alter the mannerisms of the car with Sport sharpening up the gear changes, acceleration, braking and steering.

And the 4MATIC all-wheel drive will keep you motoring in more testing driving conditions too.


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Ride Handling

One of the most pleasant surprises about the GLS is how refined it is. It’s a big old beast, but any noise intrusion from the engine and road surface is well suppressed. 

The air suspension features Mercedes’ Adaptive Damping System Plus as standard across the range. This set-up combines algorithms and highly complex sensor systems to adapt the car’s damping characteristics according to the road condition and driving situation in real time. Clever stuff and very effective.

A single glance in the direction of the GLS would suggest the ride would be a little fidgety, especially as it sits on 23-inch alloy wheels. But you would be wrong. Because, despite its size and weight, the GLS flies through the lanes with outstanding levels of grip and only a slight sign of body sway if bends are attached too eagerly.

With our unpredictable weather patterns, it’s not only the 4x4 system that will help make driving so much safer in this car. It also features Crosswind Assist, so while bridges up and down the country will be closed due to high winds, the GLS will barely notice them.

And our test car also featured an optional Off-Road Engineering package that introduced additional drive modes to tackle more demanding terrain – if any owner is brave enough to get their pride and joy dirty that is.


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021


If ever a vehicle were to make a statement by standing still, the GLS is just the model. It demands attention wherever it goes and has a road presence that cannot be ignored.

The GLS stretches 5.2 metres in length (51mm over predecessor) and is 2.15 metres across (an increase of 48mm) and 1.8 metres high. The wheelbase has also grown by 60mm to 3,135mm. No shrinking violet then!

The five-door SUV exudes power and features an almost upright radiator grille, front chrome skid plate, air inlets, twin-domed bonnet, distinctive headlights with multibeam LED headlamps and smart daytime running lights.

At the rear, powerful haunches extend from the rear doors. There are two-part tail lamps, another chrome skid plate and two chrome tailpipes.

Climb inside and the interior of the GLS oozes charm and quality, incorporating the finest materials to create a cabin fit for a king … or queen.

The seats are made from Nappa leather and feature a massage function in the front two rows. All seven seats can be heated, there are powered window blinds, a panoramic sunroof, five-zone climate control and an ambient lighting system with 64 different colour shades.

The cabin is finished with high-gloss anthracite lime wood trim, with centre panels and beltlines in Nappa leather. An Air Balance system offers cabin fragrancing, ionization and filtration and, to be honest, the list of luxurious touches goes on and on.


In The Car

Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Behind the Wheel

The powered seats with memory settings, along with a fully power-adjustable steering wheel, make finding the perfect driving position within the GLS a simple process. Then it’s worth taking a minute to take stock of the wealth of technology at your disposal.

The GLS features the latest Mercedes-Benz User Experience (MBUX) infotainment system with two large 12.3-inch screens merging into one behind a glass plate and these are the main focal point within the cabin and the nerve centre. The left screen is where all the infotainment systems are located and the right screen is about performance stats and readouts. Each screen can be personalised to taste and navigating the set-ups is very simple via a touch pad, steering wheel controls or voice activation.

There is a Burmester sound system, head-up display, DAB digital radio, smartphone integration via Apple CarPlay and Android Auto with wireless charging pads in the front and back, plus a TV receiver.

The car’s virtual assistant system is very intuitive and is activated by saying “Hey Mercedes” and asking your question when prompted. This can be tasks such as finding a radio station, calling a contact from your phone, adjusting the temperature or getting sat nav directions.

The set-up has become more advanced recently so you can now ask more complex questions such as the latest football scores, finding out how the stock market is doing and even getting restaurant recommendations dependent on location.

Second row passengers are treated to their very own on-board entertainment too with an MBUX rear tablet to take control of many of the car’s infotainment features. There are two 11.6-inch screens that allow passengers to watch movies on the go or browse the web and they also benefit from the car’s Thermotronic functions – this brings pampering treats to the second row with heated cup holders, along with temperature-controlled seats with massage function, of course.


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Space & Practicality

The Mercedes GLS is a ‘proper’ seven-seater. And by that, I mean the pair of rear seats are actually accessible, comfortable and practical enough for adults (up to 1.94 metres tall) to sit in without too much trouble. 

That’s because the GLS boasts electrically-adjustable seats throughout with an Easy-Entry function. The seats can be moved forwards or backwards, they tilt and slide and fold flat – all for ease of access. And then when you have something large to transport seats in rows two and three can be folded flat by pressing the ALL button. 

For added convenience the boot, accessed via a powered tailgate, has a sill that can be lowered by 50mm to make it easier to load heavy items.

With just the pair of rear seats dropped flat, the GLS can swallow 470 litres of kit – that’s about four full sets of golf clubs. With just the front seats in use, that limit increases to a whopping 2,400-litres capacity.

The wide-opening doors and elevated seating make the car ideal for anyone transporting young children and needing access to a child seat, and the GLS has a towing limit of 3.5 tonnes (reduced to 3.3 tonnes with the Off-Road Engineering package) and Trailer Manoeuvring Assist to make reversing easier.

Apart from the generously-sized boot, there are numerous storage compartments scattered throughout the car, including a lockable glovebox, deep door bins with a section for large water bottles, cup holders for all occupants a central cubby and plenty more besides.



Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Running Costs

The Mercedes GLS is available in three trims called AMG Line Premium, AMG Line Premium Plus and AMG Line Premium Plus Executive with prices starting from £75,610.

We opted for the high-end AMG Line Premium Plus Executive model costing £93,610, although an optional Off-Road Engineering package costing £1,495, saw the final cost rise to £95,105. 

When it comes to the running costs, the diesel-driven GLS can deliver a combined 30.7mpg with carbon emissions of 234g/km (under WLTP testing). 

This particularly high CO2 figure comes at a price and results in a high road tax charge (or Vehicle Excise Duty to give it its official name) of £1,895 for the first year. This would be reduced to the standard fee of £155 after 12 months.

However, because the GLS costs in excess of £40k, owners will be charged an extra premium car levy of £335 per year for five years.

For company car drivers, the vehicle has a Benefit in Kind rating of 37 per cent and the insurance for the GLS is the high too at group 48.


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Quality & Reliability

When it comes to reliability, the GLS normally scores relatively well in customer surveys but the company as a whole still has some work to do.

As with many premium car makers, the reliability can be an issue, especially as the technology gets that much more complicated.

The GLS certainly feels well-constructed though with a solid feel throughout the cabin and strong upholstery and switchgear.

The infotainment system really looks the part and is an area where the German car maker excels. In addition, all the running gear such as the punchy 3.0-litre diesel engine and nine-speed gearbox are tried and tested and should deliver thousands of trouble-free miles.

For added peace of mind, the GLS comes with a three-year, unlimited mileage warranty, along with Mercedes Mobile Roadside assistance across Europe.


Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Safety & Security

The Mercedes GLS has not been tested for its Euro NCAP safety rating, but shares many features with its sibling, the GLE, which was awarded the maximum five stars 

Safety systems on the car include the likes of an active bonnet for added pedestrian protection, anti-lock brakes with brake assist, attention assist, crosswind assist, hill-start assist, four-wheel electronic traction system, adaptive brake assist with hold function, electronic stability programme and a full suite of airbags.

The Driving Assistance Plus package, included as standard, introduces a wealth of driver assistance and collision avoidance systems, including active emergency stop assist, active lane change assist, active lane keeping assist, blind spot monitoring, evasive steering assist, active speed limit assist and plenty more besides.

The GLS has 4MATIC permanent all-wheel drive plus an optional Off-Road Engineering package, costing £1,495. This added fully variable all-wheel drive and transmission, torque-on-demand for traction and dynamic control, inter-axle locking for torque-on-demand clutch, low-range off-road gearing, downhill speed regulation, off-road ABS and Dynamic Select modes to include Offroad, Offroad+, Comfort and Sport.

For added security, the GLS has a high-end alarm and immobiliser.



Mercedes GLS 400 d 4MATIC AMG Line Premium Plus Executive 2021

Big, luxurious seven-seaters don’t come much better than the Mercedes GLS. It’s bold, powerful, practical and beautifully styled. It’s pricey yes, but sometimes in life, you get what you pay for.


More On This Car
Take one for a spin or order a brochure
Request a Mercedes-Benz GLS brochure
Request a Mercedes-Benz GLS test drive
By Maxine Ashford
Dec 01, 2021

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