Parkers overall rating: 4 out of 5 4.0

Take a tour around it and you’d be forgiven for assuming that the Mercedes-Benz GL-Class AMG performance wouldn’t be all that impressive.

Sure, it’s got sporty styling cues but look at the size and scale of it. Then you spot the ‘V8 Biturbo’ badges on the front wings and you begin to doubt those initial assumptions.

Lift open the enormous bonnet to reveal the sole engine choice – a 5.5-litre twin turbo petrol engine producing an astonishing 500bhp and 760Nm from just 1,600rpm. In layman’s terms that means whether the car is at a standstill or cruising at 60mph, a prod of the throttle means an instant wave of power.

The stopwatch doesn’t lie, confirming that in just 4.9 seconds the GL63 AMG will have scorched to 62mph from a standstill. Where conditions permit, this mammoth Mercedes will carry on accelerating all the way to 155mph.

Still not enough? Pay extra for the AMG Driver’s Package and the electronic speed-limiter is unlocked further allowing the GL63 AMG to nudge 174mph.

As the speedometer arcs ever further clockwise, the automatic gearshifts are barely perceptible. Metal, rather than plastic, paddles are attached to the wheel should you wish to change gear manually, while there’s a Sport mode for automatic changes, holding on to engine revs for longer, which provides a happy medium.

Naturally, all of this urgency is accompanied by a thunderous and theatrical exhaust note leaving you, or those around you, in no doubt of the GL63’s potency.

With its tall bodywork and air suspension you’d be forgiven for assuming that Mercedes-Benz GL-Class AMG handling was blancmange-like.

The reality is extraordinarily different. Let’s not pretend it’s a high-rise sports car but it is a remarkably accomplished seven-seater 4×4 that performs surprisingly well.

You can’t escape the sheer sense of scale while piloting the GL63 AMG – you feel like you’re sat in your favourite armchair, looking out of the bay window with a living room’s worth of space behind you.

Choose to keep the suspension in Comfort setting and the GL63 AMG has an appreciably softer edge to its manner but it doesn’t roll and lollop its way around bends. Selecting Sport mode sharpens up responses and it corners in a way that belies its size.

There’s a word of caution though as it’s never going to dispatch a series of tight S-bends like a smaller, lower and, crucially, lighter car would. As good as Mercedes-Benz’s engineers are, they’ve yet to overcome the laws of physics.

Uprated AMG brakes with scarlet painted callipers to signal their superior stopping power ensure the GL63 AMG’s speed can be reined in rapidly when needed, the adaptive air suspension working feverishly to prevent the heavy nose of the car diving towards the road surface under braking.

One handling trick up the GL63 AMG’s sleeve is its Active Curve System, where during cornering the car’s on-board electronics stop the wheels on the inside of the bend rotating as quickly as those on the outside, allowing the car to corner more quickly.