Porsche 718 Cayman GT4 RS 2022 first drive

Even more so than the 911 GT3, the Cayman GT4 RS feels deliciously over-endowed for firepower – well capable of putting more torque into its driven rear wheels than they can transmit to the road despite being the first car of its particular breed to wear Michelin’s very stickiest road-legal Cup 2 R tyres. Some fast Caymans have approached a similar feel over the years, but none other has felt like such an unabashed, tyre-smoking hot rod.

Accomplishing that transformation from a technical standpoint first meant finding a way to swap the existing GT4’s 414bhp 4.0-litre flat six for the 992-generation GT3’s 493bhp one; and they’re entirely different engines. Being effectively spun through 180 degrees around the Porsche’s rear axle, the incoming motor needed all-new induction and exhaust systems, and a relocated dry sump lubrication system, to make the switch work. 

Being necessarily much longer than the one in the 911 GT3, the new exhaust in the GT4 RS has a pair of rear half shafts to bend its way around on its way to the rear silencers. Producing more back pressure than the one in the equivalent 992 as a result, that exhaust system is chiefly responsible for the GT4 RS’s very slight relative deficits on peak power and torque compared with its GT3-badged contemporary.

“People can believe that we’ve deliberately detuned the engine in order to keep this car in its place if they want to,” says Porsche GT department boss Andreas Preuninger, “but it’s not true. This is a GT3 engine giving everything it’s got, revving to 9000rpm, and packaged in the mid-engined car just as well as we could do it. Believe me: it’s not holding anything back.”

Boy, don’t you know it. Part of the reason why is because the engine breathes unlike one in any other Cayman: not through its flank air intakes, but through an all-new cold air induction system with intakes positioned just a few inches behind the heads of its cabin occupants, where the rear quarter-light side windows might otherwise have been. These intakes feed a carbonfibre air box that sits on the top of the mid-mounted engine - within the passenger compartment. And the whole induction system creates the GT4 RS’s unique and spectacular engine note: one of a pure, pulsing, razor-sharp combustion howl and a convulsing, detailed sort of induction hammer the likes of which this tester has only heard before on classic track cars with open-trumpeted carburettors - and even then not to the same intoxicating effect.

From within the cabin, at the very least, the Cayman GT4 RS makes the kind of noise that you simply can’t believe can be signed off on a road-legal car in 2022. Evidently, development bosses Preuninger and Frank Walliser didn’t believe it would be, either, which is why they kept their prototypes hidden away during key stages of the car’s development from certain highly placed decision makers at Porsche, who might have otherwise have insisted that incredible howl be dialled down.

“We did a lot to filter out harshness from the engine noise,” says Walliser, “like better securing the whole system to the chassis and damping down the resonances using foam liners for the induction tracts. Originally, this engine sounded very harsh – like a chainsaw cutting its way between your ears, some said. Now it’s got plenty of bite, but not too much.”

Downstream of all that noise, the GT4 RS’s 493bhp finds its way to the road via a short-ratio PDK paddle-shift automatic gearbox (the same one used on the 991v2-gen Porsche 911 GT3 RS) and a passive limited-slip differential. For axles, it sticks with strut-type suspension front and rear, but these are ball-jointed to the chassis and are  closely related in places to the hardware used on other last-generation, GT-department 911 track specials. 

Compared with the regular GT4, the GT4 RS’s spring rates have jumped by 66% on the front axle and 40% at the rear, but since the GT4 RS’s axle tracks are wider than the GT4’s anyway (6mm front, 8mm rear), the gains in effective spring rate are less. The car has special PASM dampers and adjustable anti-roll bars, and its wheel geometry, too, can be adjusted for both camber and toe angle. Uprated steel brakes and centre-lock forged aluminium wheels come as standard, Extra-lightweight magnesium rims and lightweight carbon-ceramic brakes are optional.

Not that you need to know any of that to realise that this is a proper GT Porsche, because it’s got aerodynamic aggression to spare. Weight-saving carbonfibre-polymer bodywork comes as standard for the bonnet and front wings, which between them also duct air into and away from the front brakes via the NACA ducts and hot air outlets adjacent to the front arches. The swan neck rear wing on the car’s rump is borrowed straight from the GT3 and, along with the front splitter, it’s adjustable to create up to 25% more downforce than the GT4 manages. 

The GT4 RS uses lightweight glazing and interior door panels and carpets, too, and weighs in at 1415kg: some 35kg lighter than an equivalent Cayman GT4 PDK - and that’s only the official homologation figure. Put optional carbon brakes and magnesium wheels on your car, delete the standard-fit infotainment and audio system, and you’ll very likely end up with a GT4 RS that weighs less than 1400kg in running order, and that’s accounting for the optional magnesium roll cage if you want it. The last fast 911 that weighed less was the revered 997 GT3 RS 4.0 of 2011, which, incidentally, also made 493bhp.

On road or track, this is a seriously fast car, needless to say. Its short-ratio gearbox works supremely well with that sabre-edged flat six and makes the car zap through the gears and out of the corners really urgently, with none of the heavy-legged feel of the Porsche Cayman GT4 or the GTS 4.0. The GT4 RS needs a little winding up, just like a GT3, but at high crank speeds, it feels eye-poppingly savage. Allowing for the audible theatrics, full throttle above 6500rpm is an almost religious experience - and it’s one you might well want to enjoy through earplugs, if not through a racing helmet, on a track day.