The General Motors front-wheel drive X platform was used for compact cars from the 1980 through 1985 model years, superseding the earlier, similarly designated, rear-drive platform.

After front-wheel drive cars had become somewhat common in the North American market, first through foreign imports, and then by American-badged but wholly or partially foreign-developed cars (e.g., the Ford Fiesta and Dodge Omni), GM's X-bodies were the first American-developed front-wheel drive cars introduced for the high-volume, mainstream market. GM would subsequently migrate most of its mainstream platforms to front-wheel drive as well.

Where numerous earlier American front-wheel drive cars were aimed at the luxury market and manufactured in relatively small numbers, the GM X bodies offered an alternative to high volume imported front-wheel drive compacts—and initially met considerable sales success.

Ultimately, the X-bodies—which included the 1980–1985 Chevrolet Citation, 1980–1984 Oldsmobile Omega, 1980–1984 Pontiac Phoenix and 1980–1985 Buick Skylark—became synonymous with their design defects, and GM's mishandled response.

The X platform was the basis for the intermediate FWD GM A-body that proved much more successful. The X platform was superseded by the L-body and N-body platforms, which were derived from the J-body platform.

For General Motors, the transverse front-drive configuration had represented uncharted engineering territory. At a time the company had begun reorganizing, and began using a new engineering approach, with its divisions responsible for a single aspect of the design rather than an integrated whole. After a significantly compressed design development, the X-bodies entered production and sales—and the design's most prominent engineering deficiency, the rear brakes, became obvious.

In 1979, during even the first months of manufacture, GM made a number of revisions to the car's braking system. Automotive journalists and reviewers noted in the autumn of 1979 rear wheels' tendency to lock upon heavy braking, such as in an emergency situation, a potentially dangerous behavior compromising vehicle control. In the first year of manufacture, hundreds of complaints noted rear brake locking, with dozens of related accidents and injuries—including one death, the latter triggering a lawsuit. The National Highway Traffic Safety Administration pressured General Motors for remedial action.

GM issued a voluntary, though unpublicized recall to modify the brake proportioning valve of only the earliest manual transmission models, less than 50,000 of the already more than one million X cars on the road. While remaining publicly silent on the safety implications of the brake design, leaked internal documents demonstrated that GM's engineering staff were dubious the valve modification would suffice, even for those cars subject to the recall—and that further changes to the brake linings and brake drums were required—that could raise the cost per vehicle by $70–150, and would need to address a far greater number of vehicles.