The original Grand Am was introduced in the fall of 1972 as a 1973 model. It was based on the GM A platform (A-body) along with other cars such as the Pontiac LeMans, Pontiac GTO, Chevrolet Chevelle, Buick Century, and the Oldsmobile Cutlass Supreme. The GM A-body platform had major design revisions in 1973 that included the elimination of pillarless hardtops due to proposed federal rollover standards, but with frameless windows similar to that of a hardtop. No convertibles were produced due to those same federal rollover standards (that never were enacted). In addition to federal emissions regulations that reduced performance, new federal standards required a 5 mph (8.0 km/h) impact-resistant front bumper and a 2.5 mph (4.0 km/h) impact-resistant rear bumper, which increased to 5 mph (8.0 km/h) for 1974.