The Chevrolet Corvette Callaway Sledgehammer was a high performance one-off creation built by Callaway Cars for the 1988 model year. The Callaway Sledgehammer was one of the many Callaway Corvettes that were built using the C4 Corvette. The Sledgehammer was created to acheive incredible high speeds and featured a raft of engine improvements and upgrades which saw power reach 880hp. These performance upgrades allowed the Sledgehammer to 254mph, which was the highest speed reached by an automobile at the time.