Review: the gargantuan Mercedes-AMG GLS 63

This is Mercedes proving it doesn’t know where to stop, isn’t it?

That’s about the size of it. It’s what happens when engineers say ‘you know that huge engine we’ve got? And you know that huge car we’ve got? Well how about…’ without anyone stopping to consider whether the end result would actually be A Good Idea.

So it’s not?

I didn’t say that. But that’s the general assumption. An emphatically non-sporting seven seat SUV doesn’t need a 5.5-litre twin turbo V8, and outside of the Middle East the potential audience can barely be big enough to justify the engineering costs.

A quick recap. The GLS sits at the top of Merc’s off-road tree, the lower branches consisting of the GLE, GLC and GLA. Oh, and don’t forget the G-Class. That doesn’t follow the new naming nomenclature, probably because Merc is still surprised to be selling it in 2016.

But the GLS is new, isn’t it?

Not really. The ‘transformation’ from GL to GLS consists mostly of a gentle reprofiling of the nose and modest tweaks to the interior, suspension and powertrains. This was basically a matter of aligning the range neatly.

There used to be a GL 63. It cost around £92,000 and had 550bhp. The new one has 585bhp and costs £102,350. I suspect the price is irrelevant – the kind of people who want one won’t care what it costs. They probably won’t even give a hoot about residuals. Had a quick peak on Autotrader – it’s not pretty. Drive it out the showroom and you wave goodbye to £25k, three years down the line it’s sub-£50k.

Not pretty at all. How’s the new one?

I drove it home and hated it. Hated the overblown inefficiency of it all- not just the fuel economy, but the design, the attitude, the impression it gave other road users. It was too cumbersome, too shouty, too pleased with itself for no good reason.

But…

Then I spent another four days in it. And it got under my skin.

But let’s deal with it at face value to start with. It’s a behemoth, well over five metres long, two wide and two high. It’s a long, long way from good-looking; the nose is blunt, aggressive and crass, it’s slab-sided and conveys no sense of Mercedes’ latest design language. It’s a high climb up into it and the interior design and fixtures are last-gen Merc. It’s way behind Range Rover in terms of visual appeal and satisfaction.

But it is genuinely vast inside. Seven-adult vast. The seats all fold electrically, which is just as well because you’d never be able to reach the rear ones to raise them if you leant in from the boot. So in terms of practicality this thing trades even blows with the Volvo XC90 or Land Rover Discovery, although it’s not as intelligently packaged as the former, nor rugged as the latter.

It cruises quietly and rides very well indeed. It’s placid despite the fact that those are 21-inch wheels. Yes, really. 295/40 tyres, too.

But this must all be true of the diesel?

It is. But in order to evaluate the GLS 63 analytically we ought to ignore the AMG aspects.

Why?

Because if we leave emotion out of it what we have here is a car that’s terrifically good at acquiring speed, but much less good at losing it. That actually has too much power for its chassis to deal with (although compared with a G55 it’s a ballet dancer). That returns 17mpg without any semblance of sportiness.

The handling is vague because it weighs 2.6 tonnes before you put anything inside. Add a few family members and you’re looking at three tons heaving along a B-road. You’ll soon learn that you have to tighten the suspension up into Sport or Sport+ just to prop it up through corners that you’ll have had difficulty slowing down for in the first place.

It’s all rather disconcerting and that’s specifically due to the power. The diesel doesn’t give you hope or encouragement, but a 585bhp twin turbo V8 petrol does. It’s addictive. It sounds mighty, it charges like an angry hippo. The trouble is it’s also every bit as deflectable from its chosen course.

So it’s all a bit much?

Or just enough, depending on how you look at it. Because there is something magnificent about the unashamed way the GLS 63 behaves. Loading it up with four bikes on a towbar (electric, obvs) rack, luggage and people seemed to have zero effect on its 4.6-to-62-and-168-flat-out performance potential. And yes, you did read that correctly, the GLS 63 will hit 168mph. The mind boggles at the physics involved. Pity the brakes, which wilt when confronted with half that velocity.

You have to be wary and circumspect when threading it about – its size is intimidating both for you and other road users, and you’ll soon realise it requires a measure of responsibility if you’re even to tickle the performance potential, and if you do, you’ll discover it does have surprising grip and some control. It’s not a disaster.

There is something amusing about piloting such an obnoxiously vast machine with such an inappropriate amount of power. Every so often I pulled out to overtake, the engine gave it the full injured hippo, I did my best to guide it and when I pulled back in, couldn’t help but giggle at the sheer absurdity of it.

So you’d have one?

No. Advice time: if you want a hot SUV with actual control and ability you’re looking in the wrong place: aim your over-burdened wallet at a Cayenne Turbo S or Range Rover Sport SVR instead. If you want luxury with speed and a measure of oligarch ostentation, Bentley has the Bentayga. For the more gentrified among you, you can have a full blown Range Rover with the 542bhp supercharged V8.

But somehow even that doesn’t have the same unhinged air as the GLS 63. I think it’s something to do with the GLS basically being a ‘family’ SUV, the one you put your kids in when you want them to be safe and secure. So fitting it with 600bhp seems extra-absurd. So I kind of love that Mercedes has this in its range, it shows they have a sense of humour. A good one.