When the directors insisted that Faccioli should design a new model with the engine at the front instead of at the back, Faccioli resigned. He was replaced by Enrico, who in 1902 brought out a 1.2 litre four-cylinder model which owed much to the recently introduced Mercedes.
The years up to 1914 saw a succession of four-cylinder models of between 1,846cc and 10,082cc, as well as sixes of 7,408cc and 11,034cc. However, Fiat (known as F.I.A.T. up to the end of 1906) did not essay a popular mass-produced model until 1912, when the 1,846cc "Tipo Zero" was launched.
Post-war came the Cavalli-designed 501, with a four-cylinder 1.5 litre engine, of which more than 45,000 had been built by 1926. Alongside this, Fiat produced a very few examples of one of their few flops, the hyper-luxury V12 6.8 litre SuperFiat, of 1921-23; the 4.8 litre six-cylinder Tipo 519 was listed until 1929. In 1925 came a more modern light car, the 509, with an ohc 990cc engine, of which over 90,000 were sold up to 1929. The other principal models of the late 1920s were the 1,440cc Tipo 514, the 2,516cc Tipo 521 and the 3,740cc Tipo 525, the latter two being six-cylinder models.
At the outbreak of war, Fiat's best-selling models were the 500 and the 1,100, or Millecento, while the biggest model then available was the 2,852cc six. Little of novelty appeared in the immediate post-war years, until the advent of the over-square 1,400 four-cylinder in 1950. The last of the Topolino, the ohv 500C, was replaced by the new 633cc rear-engined "600" in 1955; this unit-construction saloon sold a million by 1960.
In 1969 Fiat took over Lancia and Ferrari; Abarth was acquired in 1971. That year, Fiat launched the fwd 127, with a 903cc ohv transverse four (a 1,049cc version is also available); the 128 is another fwd model, with 1,116cc and 1,290cc power units. The successor to the 124, the 131 Mirafiore, was available with 1,297cc or 1,585cc engines in various stages of tune. There was also a dohc 1,995cc Abarth version, with irs and a five-speed gearbox, developing 140 bhp and capable of reaching almost 145 mph in racing guise. A conventional "middle-class" car, the 132 had dohc four-cylinder power units of 1,585cc and 1,995cc. Fiat also introduced in 1973 a series-production mid-engined sports car, the X 1/9, with a 1,290cc power unit and wedge-styling.