The GS is a front-engine, front-drive, four or five door, five passenger family car manufactured and marketed by Citroën in two series: for model years 1970-1979 in fastback saloon and estate bodystyles and subsequently as the GSA for model years 1980-1989 in hatchback and estate body styles — the latter after a facelift. Combined production reached approximately 2.5 million.

Noted for its aerodynamic body shape with a drag coefficient of 0.318, fully independent hydro-pneumatic brakes and self-levelling suspension, and air-cooled flat-four engine, the GS was styled by Robert Opron, with a low nose, a two-box silhouette, semi-enclosed rear wheels and a sharply vertical Kamm-tail.

When the GS was named the European Car of the Year for 1971, the design was noted as technologically advanced, with class leading comfort, safety and aerodynamics.