The Mid-Engine Six of Your Dreams: Porsche Cayman GT4 and Boxster Spyder Revealed

The Cayman GT4 and Boxster Spyder return for the 2020 model year with exactly what Porsche's enthusiastic customers have been demanding — a non-turbocharged flat-six. This 4.0-liter engine looks to be an absolute screamer, and it's all down to the demands of enthusiasts. So if you're unhappy with Porsche's new mid-engine hotness, you have only yourself to blame.

The Roar of the Crowd

"I gave up reading forums," says Andreas Preuninger, director of GT road cars. Instead, he has his interns do it for him, asking them to give him a bit of the essence of what his customers are asking for. Even he admits he couldn't ignore the "roar of the crowd" that was so in favor of a six-cylinder engine in the replacement Cayman GT4 and Boxster Spyder, so that's exactly what Porsche has done.

Four-Point Oh, My ...

"It's got a 4.0-liter, non-turbocharged, brand-new engine," says the GT car boss, confirming one of the worst-kept secrets in the industry. While we were fairly certain it would get a six, we couldn't know exactly what iteration of flat-six would be powering the dynamic duo.

The oddsmakers figured the GT4 and Spyder would get a detuned version of the 911 GT3 and GT3 RS' 4.0-liter engine. They got the displacement right but everything else wrong. The GT4 and Spyder both get a new bespoke flat-six, based on the 3.0-liter turbocharged 9A2 Evo in the current 911 Carrera range. The huge cost to produce GT3's 4.0-liter engine, which is essentially a racing engine, made it impossible to justify at the GT4 and Spyder's intended price point.

The new non-turbocharged engine can be produced alongside the Carrera engines, even if the powertrain engineers admit that it's over 80% new and features piezo injection and adaptive cylinder control, to help it pass current and future emissions regulations.

Naturally, it gains some power over the 3.8-liter in the previous Cayman GT4. Peak power is now rated at 414 horsepower at 7,600 rpm, with maximum torque of 309 lb-ft available from 5,000 to 6,800 rpm. It revs to 8,000 rpm, keeping with the GT department's high-revving, non-turbocharged philosophy perfectly. According to Porsche, both cars boast a 0-60 mph time of 4.2 seconds, with a top speed of 188 mph in the Cayman and 187 mph in the Boxster. It also retains the six-speed manual transmission of the previous GT4 and Boxster Spyder before, which is both good and bad news. We'll come back to that in a moment.

GT3 Understudy

The engine might not be out of a 911 GT3, but inevitably the GT4 and Spyder borrow some elements from their GT3 relation. Much of the suspension is derived from the GT3, though only the top mounts are ball-jointed, for better road-driving comfort and compliance. The entire suspension system rides 1.2 inches lower than a standard 718 Cayman or Boxster, on specifically tuned PASM Sport adaptive suspension. Toe, camber and roll bars can be adjusted manually should you want to set your car up for specific tracks.

Hanging from that suspension, you'll find wheels and tires in the same sizes as on the previous GT4. The Michelin Pilot Sport Cup 2 tires measure 245/35 ZR20 at the front and 295/30 ZR20 at the rear, wrapped around newly designed five-lugged lightweight alloy wheels (20-inch wheels, in case you don't read tire codes). The GT4 and Boxster Spyder don't feature the GT3's center-lock hubs — another concession to the car's lower price point.

The new mid-engine wunder twins receive the latest Porsche Torque Vectoring mechanical limited-slip differential and Porsche Stability Management, which can be switched off in two stages for ESC-off (electronic stability control) and TC-off (traction control). There are also new dampers and the latest steering and ABS tuning. Plug all that in to the 2020 GT4's greater power, and Preuninger says that the GT4 is able to lap the Nürburgring at least 10 seconds quicker than its predecessor. That would put it under the 7-minute, 12-second time that the outgoing generation of the 911 GT3 recorded.

Aerodynamic Gains

The considerable improvement in its Nürburgring lap time — despite protestations that the GT4 and Spyder aren't track-focused but rather track-capable cars — is due in part to aerodynamic improvements. Like the old GT4, both the front and rear aerodynamic aids are adjustable, and the new rear wing has a gurney to produce a low-pressure area behind it. The biggest gains, though, have been made along the car's sides and underbody.

"We had to look elsewhere for making the downforce, which is the underbody, because we can always live with a little bit more. It's aero that comes for free because we don't have a penalty in coefficient drag due to the underbody changes. It's making more downforce, about 50% more than on the GT4 first generation, which is GT3 bandwidth at the moment," says Preuninger. The additional aero elements in front of the front wheels smooth the airflow down the sides, while also lowering pressure in the front wheelwells, to further improve downforce and high-speed stability.

Weighty Improvements

With any Porsche, and GT products in particular, there's always a focus on saving weight. The Cayman GT4 reportedly weighs in at 3,130 pounds, a noticeable gain over the old car's 2,954 pounds. Preuninger is quick to point out that the way homologated weights are legally measured has changed. Where previously a car could be optionally optimized with weight-reducing equipment, cars now need to be homologated without any options added or, indeed, removed.

Considering that (heavy) exhaust particulate filters are required in this generation, along with a larger battery and starter motor to provide stop-start functionality — another requirement — the weight gain isn't too substantial.

"There are so many [option] boxes to tick that make the car lighter, so this car nominally is about 130 pounds to 176 pounds heavier on paper, but it's only about 66 pounds heavier in the real world if you compare apples to apples," says Preuninger.

Weight-saving options include the removal of the stereo, Bluetooth communication system, and even the air conditioner, along with the addition of Porsche ceramic-composite brakes and lightweight sport bucket seats. As is typical with GT cars (depending on what market you live in), a Clubsport package will be offered, adding a half cage and preparation for a fire extinguisher, ignition kill switch and racing harnesses.

So What About That Ratio?

Preuninger admits that they only briefly considered a PDK (the paddle-shifted unit in most Porsche products) before sticking with the manual-only offering. The Auto Blip button allows you to look like you can heel-and-toe on downshifts like a pro, making talk of paddles even more redundant. He describes the previous GT4 as hitting a "sweet spot" for enthusiasts, saying: "We stick to the stick shift. It is part of the equation that works so well in the customer's view. We think the package is right for being the smaller brother of the GT3 with its different positioning."

Emissions regulations have added to the new GT4's mass, but they're also responsible for the retention of what was arguably the last GT4's biggest shortcoming — its lengthy gear ratios. Preuninger is unapologetic about that, explaining that the gear ratios have remained the same to allow Porsche to homologate the car for global emissions regulations. Changing them for individual markets would add significantly to the cost of the car.

"We don't want to make the car unobtainable or inaccessible. I think one thing we learned from the last one is a lot of people couldn't get one," says the GT boss. He added that this version will not be a limited-production run. Porsche plans on building as many as it can sell.

And the Spyder?

We've not been ignoring it deliberately, even if the old one was the poor relation to its GT4 sibling. This one isn't. It gets the same engine, the same suspension and the same underbody aero. Preuninger describes it as "an open GT" and very much in the spirit of the recent 911 Speedster. Nobody is yet predicting a model mix split, but with the Spyder now a genuine match for its coupe relation, only with the potential to open the roof, it should make a much bigger impact on the sales figures.

Pricing and Release Date

U.S. deliveries are planned for spring 2020. Prices will start at $97,550 for the Spyder and $100,450 for the GT4 (including handling fees). It will be interesting to see what kind of impact that news will have on the used Boxster Spyder and Cayman GT4 market since those cars have generally been commanding about the same price as this new model.

We'll be driving the 2020 Porsche 718 Boxster Spyder and 2020 Porsche 718 Cayman GT4 in just a couple of weeks, so stay tuned to Edmunds for more news and driving impressions.