There were 15 "2004" CP cars starting with 4Y400004 and ending with 4Y400018. These were preceded by the original 3 workhorse vehicles and the 3 Centennial cars produced for the 100th Anniversary, so the 1st CP car would be the 7th running Ford GT prototype. The CP cars all had varying purposes and represented different steps toward production trim so they would not be all the same. For example, you'd get one for vehicle dynamics, for top speed, for emissions, etc etc.