Calspan Corporation, under contract with the National Highway Traffic Safety Administration, developed improvements to the belt systems and compartment of a 1979 Plymouth Horizon and 1981 Plymouth Reliant. In addition, in subsequent model years, Chrysler incorporated structural modifications into the Reliant to improve the crash performance. An unmodified Horizon had previously been subjected to car-to-car crash tests into a Ford Mustang and a Chevrolet Citation at 70 mph closing velocity and both the Horizon and Reliant had undergone barrier crash tests at 35 mph. Certain parts of the Federal Motor Vehicle Safety Standard (FMVSS) 208 injury criteria, measured on Part 572 dummies in driver and front seat passenger positions, were exceeded on at least one of the dummies in both Horizon car to car tests and the Reliant to barrier test. The improvements significantly reduced all injury measures to levels well within the FMVSS 208 criteria when these cars were subjected to the same test conditions as the previous crash tests.