General Motors X platform (RWD)

The X-platform is a rear-wheel drive architecture that was introduced by Chevrolet for 1962 as a more conventional alternative to both the Y-platform compacts of Buick, Pontiac, and Oldsmobile, and the Z-platform Chevrolet Corvair, with Chevrolet debuting the architecture for 1962 with the Chevy II compact sedan.

Using a semi-unibody configuration, the X-platform body was a unitized body from the firewall rearward with frame rails bolted on to support the powertrain and front suspension. Initially introduced with 4 and 6-cylinder engines, the X-body was fitted with a wide variety of powerplants through its production, ranging between a 2.5L I4 and a 6.6L V8.

From 1962 to 1967, the X-body used a 110-inch wheelbase (1⁄2-inch longer than the Ford Falcon); for 1968, the platform wheelbase was extended to 111 inches (an inch shorter than the A-body).

Sharing largely unchanged chassis underpinnings throughout its 17 model-year production, the X-body underwent body redesign for 1966, 1968, and 1975. The architecture was produced across an extensive range of body styles, including a 2-door sedan, hardtop, and convertible, a 3-door hatchback (among the largest ever produced by GM), and a 4-door sedan and station wagon. The hardtop, convertible, and station wagon are exclusive to the Chevy II before 1968, with the Nova and its counterparts offered as a two-door sedan, three-door hatchback, and four-door sedan.

Exclusive to Chevrolet during the 1960s, the Chevy II (renamed the Chevrolet Nova for 1968) would serve as the successor to the Corvair in the compact segment. In Canada, the model line was also sold as the Acadian (by Pontiac/Buick dealers in place of the Pontiac Tempest) from 1962 to 1971. After exiting the compact segment following the 1963 model year, Pontiac introduced an X-body model line for 1971, with Buick and Oldsmobile following suit for 1973.

Following the introduction of the Oldsmobile Omega, Pontiac Ventura, and Buick Apollo alongside the Chevrolet Nova, the X-body was also colloquially referred to as the "NOVA" chassis, in reference to the first letter of each model name (Nova, Omega, Ventura, Apollo).

As the 1970s progressed, Buick and Pontiac would rename its X-body model lines (shifting nameplates from the A-body intermediates). For 1974, Pontiac downsized the GTO to the X-body (for its final model year before 2004). For 1975, Buick reintroduced the Skylark to replace the two-door and hatchback Apollo, replacing the Apollo entirely for 1976. For 1977, the Pontiac Phoenix was introduced, replacing the Ventura for 1978.