Unveiled: 2010 Chevrolet Corvette C6.R

DETROIT — General Motors has officially unwrapped the second-generation Chevrolet Corvette C6.R racing car, based heavily on the production Corvette ZR1. The latest C6.R, powered by a new 5.5-liter V8, will compete this year in the 24 Hours of Le Mans endurance race, as well as the 2010 American Le Mans Series.

The first significant upgrade to the CR.6 since it was introduced in 2005 was driven in part by changes in the ALMS production-based GT category rules. Whereas the original C6.R had much in common with the Corvette Z06, including a 7.0-liter V8 engine, for 2010 the updated C6.R is derived from the Corvette ZR1.

The C6.R shares a variety of major components with the ZR1, including the basic body design and aero package, as well as the production car's aluminum underbody structure and steering. The racing car has flared fenders to accommodate the larger Michelin racing tires, as well as a full-width rear spoiler and front splitter from the ZR1.

While brakes, wheels and tires are different, the biggest change is to the engine.

The ZR1, the latest version of which was introduced in 2009, is fitted with a supercharged 638-horsepower 6.2-liter LS9 V8.

In contrast, to meet pending GT2 rules, the C6.R for 2010 gets a normally aspirated 485-hp 5.5-liter LS5.5R V8 that is based on the Corvette Z06's 7.0-liter LS7 engine, with shorter stroke and reduced cylinder bore diameters. The CR.6 will use E10 fuel at Le Mans and E85R ethanol racing fuel in the ALMS.

Inside Line says: WWZD: What would Zora Arkus-Duntov do? Probably exactly the same thing. — Paul Lienert, Correspondent