It is the luxury, less powerful, more hightech version of the Chevy Corvette.
It uses the chassis and many other parts from the Chevy Corvette, but the XLR has a softer suspension, a Cadillac NorthStar V8 which gives less power than the Chevy V8. The XLR comes with a whole lot more standard features and leather and GPS and push button start ignition, etc.