Nearly every detail on the new Porsche 718 Cayman GT4 RS prioritizes performance or weight savings, from strap pulls in place of door handles to ball joints substituted for suspension bushings. A pair of cupholders are a concession to street use, but Porschephiles know exactly what this special 718 is all about. With a real motorsport-derived 911 GT3 flat-six shoehorned into the Cayman’s mid-engine chassis, the GT4 RS is a competition car for the road.

Porsche has already announced that the next-generation Cayman and Boxster siblings will transition to full electrification, which makes the GT4 RS a swansong of sorts for the internal combustion era. The news that a legit 911 GT3 engine capable of revving to 9,000 RPM redline might even fit into the Cayman at all prompted massive excitement among the company’s devoted following, though actually transplanting it into the 718 wasn’t easy. 

Before 718 Cayman GT4 RS deliveries begin later this year, Porsche invited select media to Willow Springs for a half-day experiencing perhaps the ultimate track toy from a company known for producing incredible track toys. 

Understanding the cheers that erupted after the GT4 RS debuted last year requires a quick dive into Porsche history. While the flagship 911 and its predecessor the 356 are rear-engine designs, mid-engined cars go back to the company’s earliest days, when the 550 and RSK Spyder proved that lightweight, nimble racers could keep up with, if not beat, heavier competitors with higher displacement motors.  

The company built its first mass-production mid-engine production design, the 914, in 1969, complete with a six-cylinder variant with a 911-sourced engine, the 914/6. That pricey model proved unpopular, but in 1996 Porsche went mid-engine again with the original Type 986 Boxster. The company’s first totally new car in 19 years, the first Boxster was immediately popular and credited with turning around the company’s flagging 1990s fortunes.  

After decades of air-cooled engines, purists scoffed at the Boxster’s water-cooled flat-six, codenamed M96, but a year later the Type 996 911 arrived with a larger version of the engine. Porsche never took this engine racing, however, knowing that its wet sump oil lubrication setup would cause oil starvation during hard cornering, among other issues. 

In 1999, Porsche engineer Hans Mezger designed a new dry-sump performance engine for use in the 911 GT2 and GT3 variants, developed from the mid-engine 1997 911 GT1 LeMans racer. The “Mezger engine” evolved into an even more hardcore RS (RennSport) line over the next decade, but until now the company has never put either the original design or any of its descendants into a Boxster, nor has there ever been an RS version of either the open-topped car or its Cayman coupe sibling. 

On the newly repaved Streets of Willow Springs track, the GT3 engine powering the Cayman GT4 RS screams up to 9,000 RPM, reaching peak torque of 331 pound-feet at 6,250 and flying past a peak of 493 horsepower at 8,400. All the challenges that Porsche’s engineers needed to solve—like relocating the dry sump oil reservoir, coolant hoses and vacuum tubes—fly right out the window because they also tuned the air intake mounted directly behind the passenger compartment to create the most spellbinding induction sounds imaginable. 

The 4.0-liter mill sends power to the rear wheels through Porsche’s famous PDK seven-speed transaxle, which receives a dedicated oil line and dual-mass flywheel to handle such high revs. Compared to the “base” GT4, the GT4 RS gearbox is automatic-only and also features shorter gear ratios in a nod to widespread complaints surrounding the GT4’s gearing. A mechanical limited-slip differential sourced from the previous-generation 911 GT3 helps to retain traction despite the additional torque. 

Lead-follow sessions on the Streets of Willow Springs with longtime Porsche factory driver Patrick Long and driving instructor Mark Hotchkis in front provided the perfect setting to stretch out the new engine and trans, but the Cayman’s lightweight and nimble chassis deserves just as much of the limelight, as showcased by the 1.6-mile lap Porsche used for the drive, with a series of tight technical sections and only a modest straightaway. 

The entire exercise of cramming a GT3 engine into the Boxster-Cayman chassis revolves around the clear benefits of mid-engine weight distribution. And though the GT3 engine’s high redline and power stats will attract plenty of buyers to the new GT4 RS, Porsche undoubtedly hopes that track rats will also line up for a chance to experience the final descendent of a Mezger engine where it truly belongs. 

To help the Cayman GT4 RS handle such a step up above the “regular” Cayman GT4’s 414 horsepower, Porsche bolted on an entire front end from the previous-generation 911 Carrera 4S. That pairs with stiffer springs at the front and rear, both of which widen in track (by six and eight millimeters versus the regular GT4, respectively). Ball joints also replace softer rubber suspension bushings at every opportunity. 

Setting the shocks to Sport seriously firms up the ride, but the softer mode should help with daily driving. Light electromechanical steering tuned specifically for the new chassis allows just enough feedback without excessive effort—another concession to street driving. 

Porsche’s choice of a short track didn’t highlight the aerodynamic improvements made on the GT4 RS, which include three adjustment points for the massive rear wing and four for the front splitter—this despite so much hype surrounding the swan-neck mounts for the spoiler out back, which reportedly creates 25% more downforce compared to the base GT4’s wing without any increase in drag. 

Unfortunately, the factory roll cages Porsche deemed necessary for a media track session will not be available to American buyers. But anyone hoping to take their GT4 RS out onto its native habitat will definitely want to opt for the lightweight magnesium wheels, which requires speccing the Weissach Package—adding a total of $28,890 for those two options alone onto the car’s towering $141,700 MSRP.  

As is so typical on high-performance Porsches, the Racing Yellow car at Willow Springs, without the Weissach or magnesium boxes ticked but including PCCB and a first-for-Cayman Front Axle Lift System, stickered at $162,600. The Arctic Grey car, meanwhile, climbed to $195,190 or well over $200,000 factoring in taxes and registration. 

Those numbers approach 911 GT3 territory quite quickly—though, like the GT3, anyone worried about spending such sums can rest assured that scarcity will render their concerns almost entirely moot. Still, buyers in the market for such an impressive track scalpel will find themselves hard-pressed to think of anything remotely comparable. Perhaps the only direct competition will come from the new Lotus Emira. 

Optioned with either a Mercedes-AMG turbo-four or supercharged Toyota V6, the Emira will provide significantly more torque far lower in the rev range than the GT4 RS. Tighter steering that retains the excellent feel and feedback of hydraulic assist stands in contrast to the Porsche electromechanical system, as will a price tag of about half. Unlike RS buyers, Emira customers can also choose between a six-speed stick shift or an eight-speed dual-clutch automatic. 

Whipping the 718 Cayman GT4 RS around the track is a joy, and the long-awaited combo of the Mezger engine and mid-engine chassis adds that much more magic to an already fun machine. But track driving only reveals one segment of a dual-purpose sports car’s personality, raising as many remaining questions as it answers.  

The optional lightweight carbon buckets create an uncomfortable neck angle while wearing a helmet because neither the back nor headrests can move. The electric-assisted steering’s weight, as transmitted via the same 360-millimeter wheel as the base GT4, feels light enough to dictate racing harnesses rather than three-point belts. And both the chassis as a whole and PCCB, in particular, deserve the R-spec Michelins that Porsche test driver Jörg Bergmeister used while setting a 7:09.3 lap time on the Nürburgring. 

Shod in Michelin Pilot Sport Cup 2s, gone is the feeling of racing on the ragged edge; instead, the refined combination of impeccable balance, prodigious brake bite and a rev-happy powertrain allows for the composed exploration of tire grip on asphalt, all from the comfort of a luxurious interior appointed with fine materials throughout. Here Porsche toes the line between dedicated track star and modern supercar, leaning towards the latter while pointing adamantly at the former. 

Stratospheric pricing or no, Porsche clearly believes the new 718 Cayman GT4 RS will sell out—and fast—so fans who can’t or won’t be able to make a purchase can expect to start seeing these swansongs to the Mezger engine on city streets soon enough. 

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