Prominent in this area are the termini of a stout rollcage and the entry galleys for the fuel cells. These fuel fillers exit flush with the bodywork, just below the rear hatch window on each side of the car. This is another deviation from the GT1 car, whose fuel-fill openings were quite low on the bodywork. Although the latter location was banned by the ALMS for providing a competitive advantage, the GT1 C6.R was allowed to keep the old fillers thanks to a grandfather exemption. As a new entry, the GT2 version was not similarly exempted.
All of the GT2 C6.R's body panels are constructed from carbon-fiber in the team's composite shops, with none of them carried over directly from the street car. Because of class rules, the rear wing of the GT2 car is much smaller than that of its forebear. The new car does, however, receive a lip spoiler affixed to the trailing edge of the rear bodywork; this piece comes complements of the original-equipment specifications on the production ZR1. The front spoiler has the same dimensions as found on a stock ZR1.
The chassis of the GT2 car starts with a factory-fresh Z06/ZR1 aluminum frame. To this stock structure are welded several hard points, to which the rollbar and various other items are attached through a combination of pinning and welding. The engine displaces 6.0 liters-down a full liter from the GT1 car-and runs on environmentally friendly E85 cellulosic ethanol fuel that was developed and formulated at GM's Wixom engine plant. It's mated via a torque tube to a new transaxle gearbox provided by XTRAC, the same company supplied the previous C6.R. The new unit is about 50 pounds lighter than the old one, thanks to the reduced mass of the outside case and internal components. As before, the car's generator and air-conditioning units are driven off of the transaxle.
The exhaust system terminates on either side of the car as before; however, it now exits through a tip with a new flattened-oval shape. This change was dictated by the rocker-panel dimensions, which are shared with the stock ZR1. The round design used on the GT1 car would have cut into the floor of the GT2 cockpit, so the tip was literally flattened, while preserving its original size.
Also noticeable is the absence of side splitters, which were used on the GT1 C6.R and appear on the stock ZR1. Extending the side rocker covers to ZR1 dimensions to cover the exhaust meant no room was left for these add-on pieces. Out back, the GT2 diffuser also looks very different. It's now a flat board that runs the width of the car, instead of occupying the space between the rear wheels. Gone are the distinctive vertical fins, prohibited by GT2 rules. (Interestingly, the GT2 diffuser was actually run on the GT1 car during practice at last season's Laguna Seca race.)
Inside the cockpit, things look much the same as in the GT1 car, but all of the components have been changed to match the ZR1's dimensions. The steering wheel and gauges remain unaltered, but the telemetry has been removed to conform to GT2 rules. Every parameter on the GT1 car was monitored in real time while it circulated the track. With the GT2 car, the engineering team must wait until the car has pitted to download the information the onboard systems have accumulated.
Incredibly, the pilot of the GT2 car has no conventional gauges to scan-just warning lights to get his attention and then direct him to a digital readout. The crew in the pits can no longer advise the driver of a deflating tire, an elevated engine temperature, or any other potential problem. Rather, the driver must interpret and communicate any problems he experiences to the engineers via the radio, then make a decision as to whether a pit stop is warranted.