The origins of Officine Meccaniche can be found along the shores of Lake Maggiore, Italy. There in 1855 in Intra the Gullet & Croff foundry was established and in 1897 now transformed into Ing. Roberto Zust it began to delve in the construction of road transport. In less than ten years they would be racing on circuits such as the one just outside of Brescia. In 1917 the Societa Anonima Offcine Meccaniche which made various railway stock merged with Brixia-Zust S.A. and the OM trademark was launched. World War I had spurred not only the production of military vehicles but also airplanes as well. O.M. had been involved in aeronautics since before the war and soon expanded the combined companies production in this area while also continuing the production of automobiles from the original Zust factory in Brescia.   

The first OM car, Tipo S305, understandably based on an old Zust model, appeared in 1918 with a 4712cc four-cylinder side-valve in-line engine producing 30 bhp. 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, the famous Tipo 665 Superba. The car was available in two versions, the 665N and 665S. The main difference was the wheelbase, with the 'N' longer, at 3100mm, and the 'S' at 2800mm. Both cars used a four speed gearbox and a new six-cylinder 1991cc sidevalve engine, with 40bhp @ 3,600rpm. 

Under the direction of Signor Orazi and chief engineer Fuscaldo who had considerable previous experience at Fiat, Nazzaro and Zust, OM when racing in earnest. At Monza, the new car set thirty-six international records running non-stop for six days and averaging 65 mph for the 9,375 miles covered. Brescia had been in the doldrums ever since the Italian Grand Prix had been "stolen" by their neighbors in Milan but the events in Monza and the success of several local drivers including Aymo Maggi and Nando Minoia set in the words of Giovanni Canestrini, set local pulses racing as a contemporary newspaper cutting reported:

It would come in a few months when in 1926 OM won the coveted Rudge-Whitworth Biennial Cup at the 24 Heurs du Mans. Le Mans actually consisted of two contests run simultaneously. The Grand Prix d’endurance was a straight forward long distance affair, which obviously favored the larger touring cars. Concurrent with this, however, was the contest for the Rudge-Whitworth Triennial Cup, later to be renamed the Biennial Cup, designed for the smaller cars which were run on a handicapped basis. The handicap system for the Biennial Cup established minimum qualifying distances for each class to be covered within the 24 hour period of the race. The qualifying mileage’s were originally rather forgiving, varying from 503 miles (at an average speed of 21.9 m.p.h.) in the 1100 c.c. class, to 968 miles (representing an average of 40 m.p.h.) for the larger 4 Litre cars. These minimums were increased in 1924, so that even the 1100 c.c. class had to maintain an average speed of 38 m.p.h. over the 24 hours of the race. Distance checks were performed every six hours in order to disqualify automobiles that were not maintaining the prescribed pace early in the game. Cars 20% below their established minimum distances at the six hour mark were eliminated. Similarly cars running at 15% below minimum at the 12 hour mark and 10% at the 18 hour mark were also disqualified. All those meeting or exceeding their minimums and finishing the race, would then qualify for the  Cup. However, the actual winner of the Cup would be the Marque showing the greatest proportionate excess above its stipulated minimum over two successive years!

In 1927 the factory entered a three-car team for the first Mille Miglia, driven by Minoia/Morandi; T.Daniel/Balestrero; M. Danieli/Rosa. Ferdinando 'Nando' Minoia had already by that time tasted victory at the Coppa Florio on the Brescia circuit in 1907 in a Isotta Fraschini. He also did stints with Taunus, Lorraine-Dietrich, Alfa Romeo and Benz where he drove the legendary Tropfenwagen. His co-driver in the Mille Miglia was an accomplished driver in his own right and had partnered with Minoia on a number of occasions. The Danieli brothers and Renato Balestrero were steadier than they were fast. The last driver Archimede Rosa was OM's chief test driver who knew the cars inside out and often continued his testing duties on the track.

After battling the Alfas the entire race the OMs running not surprisingly like locomotives, took the lead as their adversaries fell by the wayside. At the 21st hour of the race the leading OM of Minoia/Morandi crossed the finish line followed by their two teammates to sweep the podium and set off celebrations throughout Brescia that would last longer than the actual race. OM knew well the marketing advantages of victory in the Mille Miglia and soon the winning cars were displayed on flatbed trucks and sent on a promotional tour of Italy where they were feted as conquering heroes in countless towns. OM'S successes were to continue with a second the following year, a second plus a 1-2-3 in the 2000cc class and fifth in 1929 followed by a fifth and third in 1930 and 1931 respectively. By then the engines had been enlarged to almost 3 litres to compensate for the now ancient sidevalve configuration. Interestingly an o.h.v. twin-plug three carburetor conversion kit was provided by OM's British importer but never used in Italy. In the end as well-built as the Brescian cars were OM could not match the resources of it's larger rival and were finally overwhelmed by Alfa Romeo.

Development of the commercial models continued as well and included supercharging and an increase in engine size to 2.2-litres in 1930. In 1933 the car production facilities were absorbed into the Fiat group. 1934 saw the display of a new car, the Tipo V, with a six-cylinder 2130cc engine with an excentric  mix of sidevalves (for the inlet) and overhead valves (for the exhaust). Power output of 65bhp @ 3,800rpm. The prototype had a wheelbase of 3,000mm and a three speed gearbox but sadly actual production did not follow. OM turned is focus to solely producing commercial and military vehicles (as part of the Fiat group) and to manufacturing other industrial equipment. In 1975 it was submerged into IVECO.