The war disrupted production, which probably stopped completely after a major bomb attack conducted by the British on 3 March 1942.

[6] The year before the Great Depression may not have been the best time for the manufacturer to push upmarket, and the "Type S" did not sell in huge numbers.

The car was launched in the autumn of 1932 with a 4-cylinder 1465 cc (8CV) engine for which a maximum output of 41 hp (30 kW) at 3,800 rpm was claimed, supporting a listed top speed of 110 km/h (68 mph).

[1] The manufacturer's inventiveness was more apparent under the bonnet than in respect of the body options, which were typically conventional at best: the car incorporated a flat grill at the front, which by 1933 was perceived by some a little old fashioned.

In October 1936, with several thousand Salmson S4's sold over the previous two years, the manufacturer used the Motor Show to launch a further upgrade.

[3] In fact, the car was placed at the far end of the stand without fanfare and without any accompanying publicity campaign, so that many visitors to the show likely missed it completely.

[3] The S4-E incorporated the technically advanced features of the S4 DA such as an engine with twin overhead camshaft, hemispherical piston heads with the centrally positioned spark plugs.

[3] However, the front suspension was now refined through the addition of longitudinal torsion bars, an approach probably copied from the Citroën Traction that had appeared the year before.

[3] Commentators noted that the new engine and suspension enhancements gave rise to a combination of performance and road-holding that was among the best in class for the time.

The technically sophisticated S4 was too complicated to interest the military and the manufacturer's Billancourt factory was too small to be listed for a switch-over to war production.

[8] Production seems to have been drastically scaled back, during the early years of the war, but sources are vague on the extent and nature of any manufacturing activity, which presumably was further inhibited by the British bombing of the plant on 3 March 1942.

[8] At the end of the war, however, it was single-seater racing cars based on the chassis of the Salmson S4-61 that were supplied for the activities of the "Union Sportif automobile" which launched a competition driving school in 1945.

[5] Following the Great Depression, Britain left the Gold Standard, which for practical purposes involved a sudden and massive devaluation for the British currency.

By the time of the Second World War the British Salmson affiliate had developed local versions of the S4-D as well as a 6-cylinder S6-D (of which there was no French equivalent).