Porsche has taken the wraps off its new 718 Cayman GT4 and 718 Spyder models, each powered by a “newly developed” naturally aspirated 4,0-litre six-cylinder engine.

The German firm says, for the first time, the two newcomers share a “technical base” that includes the free-breathing flat-six and a six-speed manual transmission as well as the high-performance GT chassis.

The engine in question spins to 8 000 r/min and generates 309 kW and 420 N.m. The 718 Spyder boasts a top speed of 301 km/h, while the 718 Cayman GT4 can reach 304 km/h. Both models accelerate to 100 km/h in a claimed 4,4 seconds.

Porsche says the 718 Cayman GT4 gains a “comprehensively improved” aerodynamics concept that produces up to 50 percent more downforce without adversely affecting drag. Indeed, both models benefit from a newly designed single-chamber arch rear silencer.

This, says the firm, creates space in the rear section for a functional diffuser, which accounts for some 30 percent of the downforce at the rear axle in the case of the 718 Cayman GT4. The fixed rear wing produces around 20 percent more downforce than before.

The 718 Spyder, meanwhile, boasts a lightweight convertible top that Porsche describes as being “suitable for everyday use” since it can be stowed away under the boot lid in “just a few steps”. Unlike the GT4, the 718 Spyder has a rear spoiler that extends automatically at 120 km/h. Thanks to its functional diffuser, it is the first model in the Boxster family to generate aerodynamic downforce at the rear axle.

The high-performance braking system used in the 718 Spyder and 718 Cayman GT4 includes aluminium monobloc fixed-calliper items, while ceramic composite brakes will be offered as an option.