It is the return of the range-topping Cayman GT4 and Boxster Spyder for the Porsche 718 series of mid-engined sports cars, and according to Porsche, both top iterations of the Cayman and Boxster now share a technical base.

For starters, both are powered by a 4.0 litre naturally-aspirated engine producing 420 PS at 7,600 rpm and 420 Nm of torque between 5,000 rpm and 6,800 rpm. Drive is sent to the rear wheels exclusively via a six-speed manual transmission, and the rear axle includes a limited-slip differential with Porsche Torque Vectoring (PTV). These outputs are 5 PS/5 Nm less than the track-going 718 Cayman GT4 Clubsport‘s.

Thus equipped, the 718 Cayman GT4 and 718 Boxster Spyder both do the 0-100 km/h acceleration benchmark in 4.4 seconds, from a standstill to 160 km/h in 9.0 seconds and to 200 km/h in 13.8 seconds. Top speed for the Cayman in 304 km/h, while the Boxster attains a maximum of 301 km/h.

In both the Cayman GT4 and Boxster Spyder, fuel consumption is rated at 10.9 l/100 km, with CO2 emissions at 249 g/km. The naturally aspirated powerplant features adaptive cylinder control, which cuts fuelling to one of the two cylinder banks on partial load for reduced fuel consumption, while a gasoline particulate filter takes care of further emissions.

This engine isn’t an adaptation of the 9,000 rpm-capable unit from the 991-generation facelift GT3, but rather a re-bored and naturally aspirated version of the 3.0 litre turbo unit from the Carrera range, here forming a new engine family called 9A2 Evo, Autocar reports. The GT3 powerplant was left out for a number of reasons, according to head of Porsche GT cars Andreas Preuninger as told to Road & Track. The first is packaging, as the GT3 unit wouldn’t fit in the mid-engined Cayman and Boxster.

Secondly, Preuninger told the magazine that the GT3 engine does not react very well to power reduction. ” A detuned version does not make sense, especially considering the packaging constraints,” he said. Meanwhile, the next consideration was cost; using a GT3 engine would have pushed prices even further upwards, he added.

Aerodynamics revisions applied to the 718 Cayman GT4 see increases in downforce of up to 50% ‘without adversely affecting drag’, says Porsche, and both models benefit in this regard at the rear end from a newly-designed single-chamber arch rear exhaust silencer which creates space for a functional diffuser; this accounts for 30% of the rear axle downforce on the 718 Cayman GT4.

Meanwhile, its rear wing produces 20% more downforce than its predecessor, translating to an additional 12 kg of downforce at 200 km/h. This is balanced at the front end with a large front spoiler lip, while airflow along the front wheels is calmed by air curtains. As for the 718 Boxster Spyder, the rear spoiler is a movable item which deploys at 120 km/h, and with its functional diffuser, is the first Boxster to generate downforce at the rear axle, says Porsche.

Chassis setup on the 718 Cayman GT4 and 718 Boxster Spyder features the Porsche Active Suspension Management (PASM) system which sits the cars 30 mm lower than their mainstream siblings, while the Porsche Stability Management (PSM) can be deactivated in two steps. The 718 Cayman GT4 and Boxster Spyder have identical wheelbase and track widths, with the top Cayman 56 mm longer overall.

Both the Cayman GT4 and Boxster Spyder feature aluminium monobloc fixed caliper brakes, with PCCB ceramic composite brakes optionally available. The top Boxster now also gets ‘specially adapted’ ultra-high performance tyres which are also used by the Cayman GT4, which add up to a 10-second quicker laptime around the Nurburgring Nordschleife for the coupe compared to its predecessor.

The 718 Cayman GT4 can also be optionally specified with the Clubsport pack, which includes a steel roll bar, a hand-held fire extinguisher and a six-point seat belt for the driver. The 718 Boxster Spyder uses a manually-fitted roof mechanism for weight savings, and the lightweight convertible top ‘can cope with top speeds’, says Porsche.

Both the 718 Cayman GT4 and 718 Boxster Spyder are now ready for orders, with prices starting from £75,348 (RM394,605) for the Cayman GT4 and £73,405 (RM384,424) for the 718 Boxster Spyder in the UK, and US$100,450 (RM420,041) for the Cayman GT4 and US$97,550 (RM407,915) for the Boxster Spyder in the United States.