When the Jim Hall/Roger Penske Corvette Grand Sport Coupe appeared at the Road America 500 in September 1964 it was a complete surprise to everyone, including the Chaparral team who had entered it at the very last minute. It was only when the second Chaparral 2 could not be readied in time that the Grand Sport, chassis 005, was pulled out of Roger Penske's shop and substituted for the Chaparral as the teams second race entry.
 
Jim Hall, Hap Sharp, and Roger Penske each took turns driving the Chaparral and the Grand Sport during the course of the race. Numerous battles with the eventual race winning Mecom Ferrari 250 LM and Ken Miles' Cobra made for an exciting event. The trio drove the Corvette to a hard fought third place finish overall.