Good news everyone(farnsworth LOL) I finally got the ZR-1 last night around day 127.  Gotta say, its the best Corvette that i have driven in all of the GT's.  Its fast, and has good handling.  Only issue is that on test track with S difficulty, the veyron's that i am always put up against are impossible to pass.  The ZR-1 has a top speed of 235MPH.  the Veyrons have a top speed of 253MPH.  So its impossible to win.