The 1955 Citroën DS became famous for its hydropneumatic self-levelling suspension.
Citroën unveiled the DS at the 1955 Paris Motor Show, where its aerodynamic shape and technical features attracted enormous attention. Its hydropneumatic system used hydraulic pressure and gas-filled spheres to control suspension movement, allowing the car to maintain a consistent ride height as the load changed.
The same high-pressure hydraulic system also powered other functions on many DS versions, including braking, steering assistance, and the clutch or gear-selection equipment in certain transmissions. This gave the DS an unusually smooth ride and distinctive driving character. Its front-wheel-drive layout and streamlined body added to its technical reputation.
The DS is sometimes described simply as having air suspension, but that is imprecise. Gas and hydraulic fluid worked together; compressed gas acted as the spring while hydraulic pressure controlled the system. The related ID models offered a simpler specification, while the DS name became associated with Citroën’s most advanced version.