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. The chassis featured rack and pinion steering, with independent suspension at the front. 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. 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. Another novelty for the S4-E was a hydraulically controlled brake circuit in place of the then conventional mechanical linkage. The wheelbase was extended by . Three standard bodies were offered. The "faux-cabriolet" (rebaptised "coupé" in October 1938) 2-door four seater was listed in October 1937 at 49,800 francs. The berline, still listed as a "conduite-interieure" bodied car was priced at 50,900 francs. The rear doors on this car were hinged at the back: when two doors on the same side were opened there was no central pillar to impede access. The four-seater cabriolet was priced at 54,800 francs. As on the 4-cylinder S4-DA, customers were able to choose between a classic 4-speed manual transmission and a “Cotal Preselector transmission", but whereas S4 DA customers were expected to pay an extra 2,000 francs for the Cotal option, the Cotal transmission was now offered at no additional cost to S4 E buyers. The Salmson S4-61 replaced the S4 DA for 1939. Technically very little changed. 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. 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. At the end of the war, however, it was single seater racing cars based on the chassis of the Salmson S4-61 that in 1945 were supplied for the activities of the "Union Sportif automobile" which launched a competition driving school in 1945.