The original Grand Am was introduced in the fall of 1972 as a 1973 model. It was based on the GM A-body platform 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 5mph (8.0km/h) impact-resistant front bumper and a 2.5mph (4.0km/h) impact-resistant rear bumper, which increased to 5mph (8.0km/h) for 1974.
The Grand Am, coined by Pontiac with a name derived from two other cars in its lineup ("Grand" signifying "Grand Prix luxury" and "Am" for "Trans Am performance") was designed as American's answer to European luxury/sport sedans and available as a 4-door Colonnade sedan or a 2-door Colonnade coupe. 43,136 Grand Ams were built during the first year of production (both two door and four door models).
The Grand Am could be had with a standard 400/2bbl engine (170 horsepower), an optional 400/4bbl engine (230 horsepower), or an optional 455/4bbl engine (250 horsepower). Originally planned but never materialized was the availability of 310horsepower (230kW) Super Duty 455/4bbl that was originally set to be available on several 1973 Pontiac models including the Grand Am, Grand Prix and GTO along with the Firebird Trans Am and Formula. However, production of the 455 SD was delayed from its planned debut at the start of the model year due to emissions considerations. Production of the 455 SD was delayed until the spring of 1973 and then it was made available only on the two Firebird models. One early '73 Grand Am prototype was reportedly assembled with the 455 SD engine.