Believe it or not, for a brief period it looked as if this pair of mega-fast SUVs were going to be tested for actual utility. On the way to the emptier end of the Berkshire Downs flurries of snow began to fall, and soon some of it was sticking to the road surface. Conditions weren't exactly Siberian, but increasing stability control intervention did turn thoughts to how well the two were likely to cope if it developed into a proper white-out, and the almost certain superiority of the Range Rover Velar SV Autobiography's Scorpion Zero all-seasons over the Cayenne Coupe Turbo's summer-spec P-Zeros.
Unsurprisingly - and fortunately given our total lack of preparedness - it didn't last. The weather shifted gears and standard British No1 Winter Precipitation began to fall, the snow washed away within a few minutes. On the plus side, it did lead to some impressively splashy puddles...
Yes, it's another battle between muscular posh-roaders - haters gonna hate - but although close on power this isn't the fairest scrap in terms of pricing or market positioning. Both challengers are too pretty and look-at-me to be regarded as true heavyweight sluggers, that being the connection that brought them together, but while the Cayenne Coupe Turbo sits near the top of Porsche's SUV hierarchy, only the Turbo S E-Hybrid above it, the Velar is beneath both Range Rover and Range Rover Sport in JLR's pecking order. Although the SV Autobiography carries a chunky premium over the closely-related Jaguar F-Pace SVR, then, its £86,685 price tag is nearly twenty grand under that of the Cayenne.
The actual difference is even more than that, because the Velar has more standard kit and fewer options: the Cayenne continuing Porsche's tradition of dozens of expensive tick boxes. For a measure of the truer gap it is possible to select every single extra-cost option on a Velar and still only take it to £1,000 more than the bare-bones Porsche. Say yes to everything on the Cayenne configurator - including such delights as a £487 carbon fibre document folder and £527 leather grab handles - and the total price rises to a dizzying £153,276. That's a 718 Boxster in extras. Against which the £127,354 as-tested price for the car you see here counts as getting off lightly. By contrast, our Velar had just a single extra-cost option - £400 for privacy glass.
But there are also compelling similarities, principally a pair of V8s and identical 542hp peak power outputs. The Porsche uses a twin-turbocharged 4.0-litre unit closely related to the one in the spiffy new Audi RS6, the Range Rover has the familiar Ford-built supercharged 5.0-litre AJ-V8 that has already got its place booked at the Carbon Footprint Meadows Retirement Home at the end of this year. Both have eight-speed auto 'boxes and smart all-wheel drive systems, with the only substantial difference on the spec sheets being the Cayenne's brawnier 568lb ft torque peak - the Velar makes a still respectable 502lb ft - and the fact that despite being 115kg heavier on official numbers, the Porsche is half a second quicker over the 0-62mph benchmark: 3.9 seconds plays 4.5.
While we didn't do any drag racing, those numbers are a fair reflection of the relative levels of pace. The Range Rover is naffing quick, the Cayenne naffingly quicker. The Velar needs to summon its efforts with a slight hesitation as the gearbox works out which ratio to switch to, the turbos build boost and the engine's oily bits gather momentum - like an old dog pausing to get the scent. The Cayenne is similarly brutal under full steam, but manages to condense all the intermediate stages when a sudden request for progress is made, the engine responding like a terrier chasing a thrown cocktail sausage. Full-throttle upshifts in the Porsche also come with a noticeable torque bump, which adds excitement, if no obvious performance benefit.
The Cayenne also wins on noise, sounding more V8-y more of the time than the Velar does. Compared to the F-Pace SVR the SV Autobiography is muted at a gentle pace - it needs over 2,500rpm or the accelerator more than half way down before it turns interesting. The Porsche is more muscular low-down, and with a zingier rasp when worked hard which a blindfolded passenger would probably reckon was more sportscar than SUV, but which actually suits it well. The Velar is much more subdued than the F-Pace SVR and although it does put on a bit of aural brawn when driven hard - with a hint of supercharger whine under the exhaust - the soundtrack has a definite split personality.
When it comes to the broader driving experience it's the Porsche that does Jekyll and Hyde. In addition to standard air springs and adaptive dampers, our test car had been given pretty much a full set of extra-cost dynamic options - including the electric anti-roll Dynamic Chassis Control system (£2,315), rear axle steering (£1,448), Torque Vectoring Plus (£1,052) and ceramic composite brakes (£4,217). But even beneath those it's clear the Cayenne has a serious amount of what chassis engineers call bandwidth. The softest setting combines no-nonsense body control with a respectable level of plushness to the damping, with Sport and Sport Plus making it firmer without turning it harsh. Even over some of West Berkshire's rougher roads - many of which don't seem to have seen any surface work this century - the Cayenne's wheel travel intelligently fills dips and absorbs compressions without excessive drama.
It steers well, too, feeling impressively svelte and pointable for something that tips the scales at 2.3 tonnes. The active rear axle is undoubtedly helping out in the tighter stuff, and the torque vectoring can be felt lending a hand, too - but the bolt-on systems are building on what are definitely strong fundamentals. Traction is huge, even in slippery conditions the Cayenne rarely feels as if it's running short of grip, the steering feels properly dialed-in and, yes, those expensive carbon fibre brakes feel unfadeable under the limited thermal challenges presented by wintry conditions and road speeds.
The Velar takes a much more laid-back approach to faster progress, one that will quickly persuade most drivers to take a similarly relaxed view. It can be made to carry speed over bumpy, twisty roads, but doing so means considerable body roll and what soon becomes an uncomfortable level of vertical motion from the standard air suspension. (This is in marked contrast to the well-damped compliance of the F-Pace SVR's steel-sprung set-up.) As with the powertrain, there's a slight hesitation to the steering, a discernible gap between input and output as the softish chassis transmits loadings, even in the punchier Dynamic mode. Traction is good, despite our test car's less aggressive rubber, and it is possible to feel a rearward bias to the power delivery. But this is all likely to be happening at much lower speeds. On fast-flowing, straightish roads the SVA has no difficulty keeping up with the Cayenne, and the Velar's cabin feels a measure calmer as it does so. But in the twisties the Porsche strolls away, even at an eight-tenths pace.
Even leaving aside the significant difference in price tags, the SVA has a huge amount going for it, especially if you like the way it looks. I've not previously been much of a fan of the Velar's styling, but have to admit that the combination of Firenze red and gloss black roof made the Carrera white of our Cayenne look dull and, frankly, a bit fridgey. Light colours don't do any favours to the Porsche's frontal styling either, emphasising the size of the front air inlets it has instead of a conventional radiator grille. Parked together, the Velar really does look like the fancier and more expensive car.
It's the same on the inside, the Velar's cabin feeling like a more harmonious piece of design, if not necessarily a more usable one. The use of JLR's twin-screen InControl Touch Pro interface means the Velar has a minimal number of physical controls, with many functions delegated to the two panels. As before, the system isn't the quickest to react, and some of the UI is questionable at best: turning on heated seats requires three separate inputs. But it has uncluttered the dashboard and allowed clean swathes of classy-feeling leather and wood trim.
The Cayenne seems to be trying to be more traditional and more modern at the same time. So it still has an analogue rev counter, flanked by digital instrument screens on each side. The central touchscreen is much larger than the Range Rover's, also faster-reacting and more crisply rendered, but it still has a lower console of more conventional touch-sensitive switches. That's not a problem - many people prefer proper buttons - but what gets close to unforgiveable is the fact these haptic panels contain the greyed-out icons for options not fitted to the car, with our test car's list of obvious not-haves including the ventilated seats that only come with the pricey massage function. The modern equivalent of a blanking plate, in something worth more than some of Hartlepool's less salubrious postcodes.
The Cayenne's UI also seems to feature some very Germanic logic, with the 'Offroad' menu including an 'onroad' option. Despite the claims of coupe-ness, which amounts to little more than a modest reduction in roofline and a shallower windscreen, the Porsche is still impressively practical, with adult-usable rear space and no lack of headroom. With front seats adjusted for an average-sized driver, it actually had more kneeroom in the back than the Velar.
The tempting presence of a gelatinous (but legal) mud track gave a chance for the Velar to prove its entirely predictable off-road superiority. This definitely wasn't down to the all-season tyres, the tread pattern of which filled with gloopy mud as quickly as the Cayenne's rubber. Both cars have height adjustability and a variety of terrain modes, but the Range Rover has more traction, better ground clearance and softer suspension better able to absorb lumps and ruts. The SVA is unlikely to be a car chosen for regular trips into the mire, but it's undoubtedly capable of getting as far into the wilderness as any owner is likely to take it.
The pairing of a big, lazy V8 with a stress-free chassis is a very Range Rover combination of virtues, and apart from the angrier, shoutier and much more expensive Range Rover Sport SVR, this Velar is the quickest and most dynamically focused car the brand has created. The Cayenne comes from the other extreme - just off-roady enough to qualify as a proper SUV, but principally engineered to be an oversize performance car. Given the difference in price it's hard to give a straight win to the Porsche - the Velar definitely offers much better value. But if you are looking for a Sport Utility Vehicle on the basis of sport, the Cayenne Coupe definitely has more of it.
SPECIFICATION - RANGE ROVER VELAR SVA DYNAMIC EDITION
Engine: 5,000cc, supercharged V8
Transmission: 8-speed automatic, all-wheel drive
Power (hp): 542@6,000rpm
Torque (lb ft): 502@2,500rpm
0-62mph: 4.3 seconds
Top speed: 170mph
Weight: 2160kg (EU laden)
CO2: 270g/km (NEDC)
MPG: up to 23.0
Price: £86,685 (£87,085 as tested)
SPECIFICATION - PORSCHE CAYENNE COUPE TURBO
Engine: 3996cc, V8, twin-turbocharged
Transmission: 8-speed automatic, all-wheel drive
Power (hp): 542@5750rpm
Torque (lb ft): 568@2000rpm
0-62mph: 3.9 seconds
Top speed: 177mph
CO2: 258g/km (NEDC)
Price: £104,729 (£127,354 as tested)