In one of those twists I sit down to write this the day cities across the globe erupt in climate strike protests and Greta Thunberg's impassive face is all across the news. Naturally, the unapologetic nature of a V8 AMG G-Wagen with side exhausts or a 12-cylinder, 635hp Bentley is a guilty pleasure capable of winning over even the most hardened anti-SUV cynic. But, between emboldened environmental activism and fact we're a clumsy presidential Tweet away from another Gulf war, it would take some brass ones to sling six figures at a vehicle that makes a cruise ship seem as frugal and environmentally woke as Greta's virtue-signalling yacht.
Still, could have been worse. While the diesel is no more we could have booked out a hybrid Bentayga instead. Small mercies. Hand-wringing out of the way, which of these is actually the more enjoyable way to burn large quantities fuel and money? Neither requires a huge amount of introduction. Both have hurdles to clear in terms of PH credibility. Let's get to it...
Arguably the G63 has an easier job, given it only has to be as good as you'd hope a modernised twist on a much-loved formula might be. Meanwhile, the Bentley's best bet is not being as bad as you might fear, given the badge-engineered stigma and lack of aesthetic charm. The fact it brings 12 cylinders, 635hp, 664lb ft and 190mph potential to the table helps its cause, likewise that it's now only the second most offensive luxury SUV on the market. But even with a 'mere' 585hp, 626lb ft and top speed limited to 149mph (Mercedes optimistically claims electronically, rather than aerodynamically) the G-Wagen is off to a winning start in the charisma stakes. And not just because I'm a sucker for any V8-powered vehicle with side exhausts.
Cruise ship comparisons might seem like lazy journalese. But that's what driving the G63 feels like, the dull throb of a huge engine somewhere deep below a constant presence at any speed. It's soothing in its way and a constant reminder you have power to spare in pretty much any driving situation. That was there in the old 463-series AMG G-Wagens too of course. The shock with this one is those ship comparisons no longer apply to the way it steers.
You'll likely be aware Mercedes has (slightly) moved with the times and updated this new-generation G with independent front suspension in place of the live axle of old. From the rear you still have that reassuringly old-fashioned sight of a diff casing hanging beneath a boxy body and promise of lurid axle articulation in the rough. But Mercedes wisely accepted improvements in handling and steering response were worth the sacrifice in 4x4 cred.
Besides, in all other respects the new G is utterly faithful to the experience of the old one. In isolation you'd be hard pressed to tell it apart, though when you park them next to each other you realise how much bigger (especially wider) the new one is. It's like the G-Wagen we always knew and loved, but more so. And has enough of the character features - locks that sound like a .50cal Browning being cocked, door seals so tight it takes at least two slams to close them properly, external hinges and suchlike - to remain honest to the traditions. Inside though it genuinely feels like a modern vehicle, rather than a patchwork based on four decades of Mercedes parts bin plundering. Never has that giant, widescreen display looked so natural either, the square-cut interior the perfect setting, while the functionality and interface remains as slick as ever. Touchy-feely stuff is absolutely top-notch too, with everything your fingers brush against feeling reassuringly solid and well-built. This is absolutely Mercedes on its game and as worthy of a six-figure price as any top-spec S-Class. Just one you'd feel happy clattering over gnarly rocks, should the mood take you.
It seems shallow to fixate on stuff like this but, before a wheel is turned, the Bentley feels on the defensive by the same measures. It's an odd mix, the traditional fine craftsmanship juxtaposed against generic VW group bits. The typical riposte is that most Bentley owners won't have driven a Skoda so won't be aware the nav graphics look the same. But for all the lovely leather, soft-touch Alcantara, turned aluminium and expensive wafts of hand-stitched upholstery, there's no escaping the fact too much of the kitsch chrome trim feels plasticky to the touch next to the Mercedes' reassuringly expensive kiss of cool metal. Inside and out the Bentayga still fails to put sufficient distance between itself and the suspicion it's a load of Bentley styling cues hurled at a generic luxury SUV platform. There had best be some magic in the way it drives, put it that way.
Our photo location provides opportunity to get a bit of dirt on the tyres, with due deference to the fact both are running expensive looking 22-inch wheels and nowhere near enough sidewall to protect against Peak District gritstone. The Bentley has £5,080-worth of All Terrain Specification and there's plenty of evidence it's way more capable off-road than any owner will likely need or explore. But there's no escaping the G63 feels absolutely at home here, even on big wheels. As Matt tip-toes along the flat gravel path, teeth clenched against every bump and clonk, I'm cheerily romping away over adjacent rocks and ruts happy as a pig in the proverbial. G-Wagen the better 4x4? Shock of the century there...
On the road the G63 feels impressively gentrified too, at least compared to its predecessor. There's still just a hint of body-on-frame shudder and it feels unavoidably top-heavy in traditional 4x4 fashion. The spring rates required to contain that in more dynamic situations mean a brittleness over secondary lumps and bumps and the sportier damper settings are pretty much redundant, given there's only so fast you'd want to attack a corner in this thing. It does at least show a degree of interest in going around them, which is a step up. Given how much torque there is, a nine-speed transmission (18-speed if you include low range) seems overkill, shuffling away like a CVT when really you want to lean on the mighty turbocharged huff. Other than that the G63 is - shockingly - a car you can now make some degree of progress in. And it sounds mega, meaning some return on those tenners you're pouring into the tank.
No doubt, the road is the Bentley's last chance to prove it has something to offer. So, in a way I'm relieved to be unexpectedly blown away. The W12 has become as much a Bentley signature as the winged 'B', meshed grilles and the creak of leather upholstery. The contrived bark at start-up is a little footballer, but once under way this engine is every bit as mighty as the stats promise. We're long past the moment where we can be shocked at how technology can mask unfavourable SUV bulk. But, all the same, the Speed has the power to surprise.
For all that swept capacity the W12 feels resolutely turbocharged, albeit in a thrillingly naughty manner when that massive whump of boost kicks in. Where even the AMG V8 can feel a little breathless against two and a half tonnes the Speed's sheer grunt makes a mockery of the kerbweight, the acceleration ferocious and as amusingly incongruous as you'd hope for in a proper Bentley.
So long as you're not unfortunate enough to glimpse your reflection in a window you could easily kid yourself you're in a Continental or Flying Spur, given the more car-like seating position and surroundings. Response to the small, chunky steering wheel is way sharper than it has any right to be and, thanks to its 48V architecture, and the trick air suspension and anti-roll tech it powers, the Bentayga feels genuinely chuckable. This is clearly many levels of wrong, yet feels so right.
Ride and refinement are where the Speed really shows its class. At a cruise it's effortlessly quiet and relaxing, the suspension isolating you from whatever may pass beneath those big wheels. A car with so much weight up high and so little sidewall below has no right to be this comfortable but the Speed will waft you from one OMFG fill-up to another in utter tranquillity. Yet it simultaneously maintains perfect body control for making serious cross-country progress when the mood takes you. Everyone will hate you, especially if you select the unnecessarily vulgar Sport mode with its Golf R style farts and pops. But, frankly, you won't give a toss. Probably not official Bentley marketing terminology, but honest to the brand DNA.
Thus, a challenge seemingly favouring the Mercedes has been flipped around. It sounds like damning with faint praise to say the G63 is exactly as good as you expected. The Bentayga, likewise, is as flawed as you might have feared. And yet pulls an unexpected rabbit out of the hat with the sheer gusto of its driving style.
There has to be a winner though and it's the car that best combines off-road cred, civilised road manners, an arch mix of traditional looks and modern style all topped off with an unapologetically excessive and powerful motor. So, if it were my money ... I'd buy a supercharged Range Rover SVAutobiography Dynamic.
SPECIFICATION - BENTLEY BENTAYGA SPEED
Engine: 5,950cc W12 twin-turbocharged
Transmission: 8-speed automatic, four-wheel drive
Power (hp): 635@5,000rpm
Torque (lb ft): 664@1,750-4,500rpm
Top speed: 190mph
Weight: 2,483kg (five-seater)
MPG: 19.2mpg (WLTP combined)
Price: £182,200 (£214,440 including options, comprising All Terrain Specification £5,080; Centenary Specification £1,385; City Specification £4,440; Touring Specification £6,350; Front Seat Comfort Specification £2,875; Bentayga Blackline Specification £5,330; 'Naim for Bentley' premium audio system £6,780)
SPECIFICATION - MERCEDES-AMG G63
Engine: 3,982cc V8 twin-turbocharged
Transmission: 9-speed automatic, four-wheel drive, low-range transfer case
Power (hp): 585@6,000rpm
Torque (lb ft): 626@2,500-3,500rpm
Top speed: 137mph (limited, raised to 149mph with optional AMG Driver's Package)
MPG: 21.4mpg (WLTP combined)
Price: £143,370 (£149,310 with options, comprising 22-inch AMG wheels £2,440; AMG Driver's Package £2,000; Designo Sea Blue Blue Metallic paint £1,750; Winter Pack inc. auxiliary heater and heated windscreen £1,750)