Engineers at Porsche’s motorsport division have liberated an extra 79bhp and 15lb ft from the Cayman’s naturally aspirated 4.0-litre flat six, which redlines at 9000rpm. That takes the total outputs to 493bhp and 332lb ft for a 0-62mph time of just 3.4sec and a top speed of 196mph.
Power is sent to the rear axle through a seven-speed PDK automatic gearbox, which shifts “at lightning speed”, according to Porsche.
Weight has been slashed by swapping the bonnet and front wings for carbonfibre-reinforced plastic items, installing lightweight carpets, replacing the door handles with pull straps, reducing the amount of insulation and installing a lighter rear windscreen. These measures combine with the engine modifications to give a power-to-weight ratio of 348bhp per tonne.
Porsche has also further optimised the GT4’s aerodynamics. A swan-necked rear wing based on that used by the 911 RSR GT racer, new air vents and adjustable front diffuser – together with a 30mm drop in ride height compared with the standard Cayman – are said to increase downforce by as much as 10% over the GT4, and in track-oriented Performance mode that climbs to 60%.