Officine Meccaniche (OM) was an Italian car and truck manufacturing company, founded in 1899 in Milan as Societa Anonima Officine Meccaniche.
The inception of the company had resulted from the merger of two companies,Grondona Comi & C and Miani Silvestri & C. Originally, OM manufactured railway stock. Car production started in 1918, using the plant of the former Brixia-Zust (Brixia-Züst), just after OM took over Zust car company of Brescia, Northern Italy.
The first OM car, Tipo S305, primarily an old Zust model, appeared in 1918 with a 4712cc four-cylinder side-valve in-line engine. Further models were Tipo 465 (with a 1327cc four) in 1919, Tipo 467 (1410cc) and Tipo 469 (1496cc) in 1921. 1923 saw an all new model, Tipo 665 'Superba' with a 2-litre six-cylinder engine. This model was extremely successful in racing - won top five positions in 1925 and 1926 at Le Mans but the grestest achievement was the victory in the first Mille Miglia race in 1927 winning the first three positions. Some cars were equipped with Roots superchargers.
OM was taken over by the Fiat Group in 1933 and in the following year, passenger car production ceased. OM became a commercial vehicle manufacturer.
In 1975 OM was absorbed (as part of the Fiat Group) into IVECO.