Porsche's star turn at the Detroit Auto Show is the sensational new 918 RSR, a stunning race machine that looks into the future.
Although it takes its name from the 918 Spyder - the ultra green supercar unveiled during Geneva 2010 - this is a very different beast. Designed wholly for speed on the track, the 918 RSR does not have a conventional petrol-electric hybrid system like the Spyder did, but a highly innovative 'flywheel accumulator'.
Instead of a passenger seat you'll notice there's an unusual cylindrical canister - that's the flywheel accumulator. Each of the 918's front wheels has an electric motor/generator, which can both drive the wheels for extra oomph or generate electricity during braking.
The energy they generate is captured and stored in the accumulator, which can spin to a dizzying 36,000rpm. The driver can press a button at any point and unleash this energy back to the motors for an instant hit of power - a kind of futuristic rocket boost, if you will.
Not that it lacks power in the first place, though: a mid-mounted 3.4-litre V8 engine develops 555bhp at a superbike-like 10,300rpm. That added to the electric motors' combined 201bhp makes this a 756bhp racer.
Elsewhere the car is more conventional, if still quite spectacular, with the most obvious change from the 918 Spyder being the fixed roof.
Porsche says the 918 RSR is a test bed for the accumulator technology, though there's a chance we could see the car hit the Le Man 24-hour race in a year or two.
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