April 30, 2008 When the preliminary performance specs for the new 2009 Corvette ZR1 appeared on the radar late last year ahead of its debut at the North American International Auto Show in Detroit, predictions were for a supercar producing 620 horses and topping 200mph, making it the most powerful and fastest automobile ever produced by General Motors. Now with the release of the certified power ratings there's no cause for disappointment, in fact it seems that initial predictions were a little underdone. According to Chevrolet, the ZR1's hand-built, supercharged LS9 V-8 engine will produce 638 horsepower (476 kW) and 604 lb.-ft. of torque (819 Nm) - an output of almost 103 horses per liter - and will achieve a top speed of 205 mph (330 km/h). On top of that, although fuel economy testing has not yet been completed, engineers remain confident that the ZR1 will be the most fuel-efficient 600-plus-horsepower car on the market.

Set to go on sale in the US this summer and in Europe towards the end of 2008, the ZR1 will feature a six-speed, close-ratio, race-hardened manual transmission, a new high-capacity dual-disc clutch, Magnetic Selective Ride Control (with track-level suspension and suspension tuning for more than 1g cornering grip), a head-up display, plus the industry’s first production version of a positive-displacement Roots-type supercharger with a unique four-lobe rotor design.

See our previous coverage of the ZR1 for further details and loads more pics.

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