2021 Mercedes-AMG GLS 63 4MATIC+ review

They say it’s one for ‘family-oriented fans of high-performance’ though is the Mercedes-AMG GLS 63 4MATIC+ all a bit much?

The GLS is the ‘S-Class of SUVs’, according to its maker. That conjures ideas of serene, luxurious motoring with room for the kids and the means to tow the boat on grand adventures. So what happens when AMG does its thing to the biggest Merc SUV? Well it means the family will get there in rapid quick time as the seven-seat GLS 63 isn’t spared any of the performance enhancing trimmings.

Like the recently released GLE 63 S, it’s powered by the 4.0-litre twin-turbo V8 which is also used to spin the wheels of the low slung GT models. But here it’s got a lot more work to do pushing 2.7 tonnes. The eight spews forth 450kW, with 850Nm of torque oozing from 2500 to 4500rpm. Just because they can, it’s resting atop AMG’s active engine mounts which can stiffen in the racy drive modes to help negate the weight transfer of the big donk in the hope of sharpening the turn in.

The V8 has been hybridised with the inclusion of an integrated starter-alternator, the slim electric motor sandwiched between the engine and transmission. Making 16kW and 250Nm, it can add a brief squirt of oomph to help motivate the mountain of mass off the mark, while it can also dump some torque in to briefly boost its overtaking prowess. It also generates the juice for the 48-volt electrical system. This allows for longer engine-off periods and, in the hotter months, that means your air con doesn’t go limp in eco mode. It makes for more seamless restarts too. Thanks to all the squirt, AWD and a fast shifting auto, this mammoth hits 100 in a scant 4.2sec, as they claim. Matching the 11.9L/100km fuel consumption number will require restraint. The long term average for this vehicle was sitting at 15.6L/100km, while we saw figures as terrifying as 22.9. A partial nod to impending climate change doom is cylinder deactivation, for when the full 450kW is not required. Which, surprisingly, is not very often. It switches between four- and eight-cylinder modes frequently. You may detect a slight faltering of the exhaust rumble, and note the little dashboard light illuminating when it does.

The trans used here is the AMG Speedshift TCT, which is not to be confused with (though often is) the MCT version used in the E and C lines. Here TCT stands for torque converter transmission, where the MCT has a wet clutch pack arrangement on the end of the box for a more direct hook-up. The SUVs don’t require such hardware, the TCT offering better low speed refinement on both take-up and when creeping about in traffic. But with AMG-fettled software, the nine-speed auto can still bang the shifts through when required and is able to drop multiple gears at once; kick it in the guts and it’ll downshift from ninth to fifth quick smart.

The GLS is air sprung while the 63 gets AMG Ride Control with unique spring rates and the damping characteristics firm as you progress through Comfort, Sport and Sport+ modes. It has pneumatic self-levelling and variable ride heights while helping the cornering cause is active roll control thanks to the 48v system. These electro-mechanical actuators on the sway bars stiffen to keep body movements leveled in the corners and they relax on the straights to improve the ride. The AWD system is variable, ranging from 50:50 to 100 per cent rear when needed, and there’s an electronically controlled locking rear diff to maximise traction. The latter you might detect binding slightly on tight, slow turns and is the only real giveaway of the heavy duty AMG hardware underneath this moving mansion.

We reckon the EQ hybrid system marries better with the inline six of the AMG 53; there’s no hesitation from a halt in that machine, where this isn’t as snappy. That’s likely to do with the V8 needing a mite longer to fill the cylinders and get those big turbos going. That and the fact the GLS weighs 2700 plus kilos. Once in motion, it rolls on in rather convincing fashion; there’s plenty of surge in the tank below 3000rpm. But it pulls best at the 4000rpm mark, going ape crazy to 7000, the cylinders pumping fast and hard.

In Comfort mode, the ride is settled for an AMG, though if you’re after more serene passage on the school drop, buy the $169,300 GLS 400 instead but refrain from optioning the big wheels. The 400 really is all the luxury SUV you’ll likely need. It’s a real torquemeister that will go much further between fill ups. But the $272,300 63 is the manifestation of today’s need for excess. And you’ll look better posing in front of it for your Instagram followers.

The GLS 63 does go hard, though the following needs to be considered in the context of a 2700kg SUV. Find the right drive mode for your mood (and your six passengers – there are enough modes to satisfy everyone) and this moves in an astounding manner. The dampers react quickly to the bumps but it’s the roll control that helps it turn. The unyielding weight transfer is effectively dealt to, so the 63 transitions through the bends tidily. The GLS is long, so it’s stable, and with screeds of rubber, it holds on. And this is aided further by the AMG Dynamics with brake-activated torque vectoring nipping away on all four wheels. The steering remains rather aloof, and the brakes sure work hard, as does the fuel pump. It’s not overly engaging, yet it’s a quick way to move bods effortlessly across all roads. There are even a few trail modes for the 63, but those wheels and tyres won’t like the punishment.

The cabin is swish with the twin digi-display dash. There are nine million ways to configure these and 65,000 different means of controlling it all, while the AMG-specific readouts will excite your inner nine-year-old. The seats have AMG support about them but enough padded comfort too. Dive into the touchscreen, bring up the Comfort menu and dial in a hot relaxing back massage. Then fiddle with the energising comfort settings to ensure the mood is right and you’ll feel relaxed and refreshed when you arrive at your destination, in record quick time if you’ve managed to tap those 450kW.

The GLS is a whopper; long and wide which is bad news in most car parks. Merc has included every parking assistant known to help out, but things like extra big rear doors, while they help entry, are hard to open in tight spaces. Best use the valet parking option where you can. But the size delivers the interior space of a full-size seven-seater. There is generous passenger space in all seven positions, and the boot is huge. The seats are electrified, all moving and folding with a touch of a button, albeit very slowly.

The GLS 63 wouldn’t be our first choice AMG SUV. That’d probably be the GLC. Need a seven-seat performance wagon? Unfortunately you can’t fit the seven-pew option to the GLE 63, yet you can with the 53, which we think is probably the better all round bet anyway.