the car's 1465 cc four-cylinder engine initially placed it in the 8cv car tax band, which would have placed it alongside lower-priced cars such as the peugeot 301 and the renault monaquatre, but the salmson's levels of technical sophistication and equipment, as well as its price, indicated that it was intended for a more aspirational clientele than these comparably sized cars. within a few years the s4's four-cylinder engine had in any event increased in size to a point where the car sat in the 10cv car tax band, which moved the s4 up half a class as well as providing customers with a more convincing level of performance.