The Voisin C18 was a large passenger car produced between 1930 and 1935.

The C18 was introduced at the 1929 Motor Show. The car expressed Voisin's continuing interest in the silence, smoothnesss and inherent balance of the 60-degree V12 configuration which he had first explored with the C2.

The only C18 in France retains its V12 power unit although it has non-factory coachwork. It attracted press attention in 1958 when it appeared in Auto-Journal.

In its first incarnation the C18 was fitted with a 3,900cc unit, which was soon replaced by a bigger 4,885 cc unit. The C12/C16 chassis was chosen for this imposing engine.

The only other significant change in specification happened in 1931, when a single-disc clutch replaced the original multi-plate unit. The last chassis left Issy in 1933. The model was available in five basic versions in the first year. This was as a bare chassis, five-seater saloon, 2/3 seat coupé, six-seater saloon and seven-seat limousine.

The standard saloon gained two extra seats in 1931, the coupé was dropped and a seven-seat coupé-limousine made its appearance. By 1932, the options had narrowed down to bare chassis, a saloon, a limousine and a coupé-limousine. By 1933, only the bare chassis was offered.