The Porsche 918 Spyder is on the road. The first street-legal prototypes, dressed in camouflage bodies reminiscent of the iconic 917 endurance racers of the 1970s, have begun testing and development on the roads around Stuttgart.

The 918 will go into production at the end of September 2013 as planned, with the first customers receiving their vehicles before the end of the year 2013 is out.

The focus of road testing is on the interplay between the individual drive components; the combination of a big combustion engine and two independent electric motors - one on the front axle and one in the drivetrain, acting on the rear wheels - poses completely new demands on both mechanical and electronic control systems.

BIG NUMBERS

The car's hybrid powertrain - a 419kW 4.6-litre V8 engine, an 80kW electric motor on the front axle and a 90 kW electric motor on the rear axle - represents a new set of engineering challenges.

The prototypes have a combined output of more than 566kW, taking them from 0-100 km/h in less than three seconds and and on to more than 325km/h flat out. Using a 6.8 kWh lithium-ion battery, the 918 can travel more than 25km on electricity alone at up to 150km/h.

Porsche board member for research and development Wolfgang Hatz explained: “The control systems are a critical component of this car, requiring all our expertise in development.”

‘FUN TO DRIVE’

“These control systems and the development of the software to go with them will have a major influence on the feel of the car - that elusive 'fun-to-drive' factor which, for me, is not negotiable.”

“They will also have to deliver a combination of minimal fuel consumption and maximum performance that is the reason for the car's existence.”

The 918 has been designed as a plug-in hybrid vehicle combining a high-performance combustion engine with cutting-edge electric motors for supercar performance: on the one hand, the dynamics of a 566kW racing machine; on the other, fuel consumption in the region of three litres per 100 kilometres.

Part of that 'fun-to-drive' factor is down to light weight, thanks to a full carbon-fibre monocoque with unit carrier, fully adaptive aerodynamics, adaptive rear-axle steering and the upward-venting “top pipes” exhaust system.

In the process, the 918 Spyder is offering a glimpse of what future Porsches may be capable of.