Porsche is showcasing the future production version of its 918 hybrid project – and stealing the limelight at this week's Detroit Auto Show – with this 756hp racecar, called 918 RSR.
The new model takes the powerplant originally showcased in the 918 Spyder at the 2010 Geneva show and builds on its power and efficiency. Its V8 motor (Porsche hasn't revealed its capacity yet but acknowledges that it's a development of the RS Spyder racer's 3.4-liter unit) produces an extra 55hp, taking it to 555hp at a heady 10,300rpm.
That grunt is fed through the rear wheels via a six-speed paddle-shift transmission, while a pair of front-mounted electric motors contribute an additional 201hp to give a total of 756hp. They use energy stored during braking in a flywheel spinning at up to 36,000rpm, and their power is called up manually by the driver pushing a button.
The flywheel system, which has potential weight benefits over heavy battery cells, is a development of the setup already used by Porsche's current hybrid racer, the 911 GT3 R Hybrid. It uses technology commissioned by Porsche and built by a division of the Williams F1 team.
Porsche claims the system can provide up to eight seconds of continuous supply when fully charged, and that it offers a torque vectoring ability to improve agility and steering response. However, in the 911 GT3 R Hybrid, the electric motors can also be used to help reduce fuel consumption, cutting the number of pit stops required or allowing the vehicle to run with less fuel on board.
The 918 RSR's construction focuses on keeping the car's weight to a minimum. As with the original Spyder, its monocoque chassis is made from carbon fiber-reinforced plastic (CFRP). But unlike the Geneva show car, the RSR has a hard-top and doors that open vertically.
It's widely believed that the shape of the RSR – huge rear wing excepted – is that of the eventual 918 production model. Many of the core features of the 918 Spyder remain, including the deeply scalloped rear bodywork, side-mounted exhausts and air intakes at either side and on top of the rear cowling.
The number carried by the Detroit show car – 22 – pays tribute to a 917 short-tail coupe that won the 1971 Le Mans 24 Hours in the hands of Helmut Marko and Gijs van Lennep. Its distance record – 3315.21 miles at an average speed of 138.13mph – stood until last year's running of the classic enduro. The car's color scheme is a blend of what Porsche calls “liquid metal blue” and the orange commonly used on the firm's hybrid projects.
The cabin features a slice of race-bred purity – the hybrid flywheel replaces the passenger seat – but it still looks realistic and luxurious enough to give a strong hint at the eventual 918 production car's interior.
The fascia and center console look plusher and less extreme than in the original concept, with a mixture of bare aluminium and brown leather. Porsche claims that the second of these materials “cites the history of the gentleman driver.”
The Spyder's touch-sensitive control interface has been replaced by a simpler setup with rocker switches, and there are now gearshift indicator lights integrated into the leather-clad steering wheel. There's also a display to inform the driver of the current charge levels in the brake energy recuperation system.
The RSR's appearance at Detroit is part of a carefully phased introduction of a hybrid "halo" car by Porsche. Like the 911 GT3 R Hybrid before it, the new racer is now set to be used as a testbed for the hybrid systems in motorsport. An appearance at the Nurburgring 24 Hours in the summer is considered extremely likely. On its debut in the race last year, the 911 GT3 R Hybrid led for more than eight hours.
Porsche could then wheel out the production version of the car in early 2012. It is unlikely to rush it out by this autumn, preferring to further develop the hybrid systems and avoid overshadowing the arrival of the next-generation 911 at September's Frankfurt motor show. The company has taken letters of intent and deposits for the car, even though the final price has yet to be confirmed.
John McIlroy/Autocar