Porsche Built a Cayman 5.0 (8 Cylinders) and a Quad-Turbo 911, But Not For Sale

Porsche is currently polishing the final details of the 718 EV, which has been confirmed to ride on an all-new platform. The all-electric sportscar is rumored to come in both coupe and convertible form and should bow in 2025, overlapping with the final run of the gas-powered 718 Cayman and Boxster. However, this reality could’ve been quite different had the industry not pushed so aggressively for electrification. For one, did you know that Porsche had built a 718 Cayman with a 5.0-liter 8-cylinder engine?

Despite the excellent driving dynamics and—legislation be dammed—the sheer advantage of being on sale in this difficult era—the turbocharged four-cylinder versions of the current 718 Cayman and Boxster, which make up the bulk of the range, still receive their fair share of criticism.

The Stuttgart automaker has addressed this by giving us no less than three naturally aspirated flat-six tiers to choose from. In the order of their ferocity, we have the 718 Cayman and Boxster GTS 4.0, 718 Cayman GT4, and 718 Spyder, along with the 718 Cayman GT4 RS—the last one is in the image above, with the text being added by us. There’s even a 718 Boxster Spyder RS coming out later this year and you can check out a tester in the CarSpyMedia video at the bottom of the story.

The Cayman 5.0 flat-eight prototype

Had the pressure to cut emissions—even for sports cars—not been so great, perhaps Porsche had maintained the six-cylinder status its modern mid-engined sportscars have enjoyed since the 986 Boxster was introduced back in 1996.

Would that path have led us to enjoy an eight-cylinder 718 Cayman? Probably not, as that would’ve allowed the better-balanced mid-engined sportscar to one-up the iconic 911. So, why did Porsche build a midship machine with more than six cylinders, then? As it turns out, this was a prototype and was initially destined for a much more important project, one that never materialized.

In an interview for British digital car magazine The Intercooler (subscription required), Porsche eFuels manager Marcos Marques explained that the production four-cylinder 718 Cayman had a much more menacing sibling, namely a 5.0L twin-turbo flat-eight. This running prototype was a test mule for a halo vehicle that was supposed to replace the 918 Spyder.

The engineer doesn’t mention anything else rather than the project’s cancelation. Even so, given the present emissions situation, we imagine the said engine was part of a hybrid powertrain, since, you know, the 918 Spyder already came in such form.

Perhaps the project in question was the Vision 918 RS, a concept the carmaker presented during its Porsche Unseen marketing initiative in 2020. In the official release, we were told the proposal never made it past the stage of a 1:1 scale hard model, with this representing a fascinating new evolutionary stage of the Porsche 918—you’ll find a few images in the gallery below.

The 911 almost stole the Bugatti Veyron’s quad-turbo ethos

In the article, the publication also talks about other stillborn performance projects from Porsche and the VW Group and all we can mention here is that the Zuffenhausen automaker experimented with a quad-turbo 911 in the previous decade, which was obviously inspired by the Bugatti Veyron (by the way, here’s how much it cost to rebuild this salt water-flooded Veyron).

If you ask us, such machines used to rock the car world in the days when the late Ferdinand Piech was in the driver’s seat—arguably his most influential era began in 1999 when Audi acquired Lamborghini, with concepts and production models like the VW Phaeton, the VW Touareg, the Porsche Cayenne and Bentley’s entire modern-era range following.

And while the British automaker is dropping the W12 soon, there are plenty of signs that the VW Group and Porsche aren’t giving up our beloved internal combustion engines that easily.

For one, Porsche is arguably the most visible carmaker in the world when it comes to eFuels. And, we’ll remind you these synthetic fuels are at the center of the lobbying Germany and other countries did to finally convince the EU that the 2035 passenger car and light commercial vehicle ICE ban can make an exception.

Besides, Audi and Porsche are scheduled to enter Formula One in 2026 when the rules change, but this is another story for another time.



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