Bologna, discontinued 1967) was an Italian brand of sports car automobiles, usually abbreviated to O.S.C.A., OSCA or Osca.
It was founded by Ernesto (engineering manager) and his two brothers Ettore, and Bindo Maserati (operations managers). The brothers left Maserati after their ten-year contract with Adolfo Orsi had terminated. Ten years earlier, in 1937, the remaining Maserati brothers had sold their shares in the company to the Orsi family, who, in 1940, had relocated the company headquarters to their hometown of Modena, where it remains to this day.
The O.S.C.A. factory was at San Lazzaro di Saveno outside Bologna, where Maserati were originally made 1926 to 1940. Their basic business goal was to develop an automobile to compete in the 1100 cc racing class.
O.S.C.A.'s first automobile was the MT4, for Maserati Tipo 4 cilindri. The 1092 cc engine (72 PS (53 kW; 71 hp) at 6000 rpm) had a FIAT-derived block, alloy head, and the bodywork was built as a two-seater barchetta. The MT4 first raced in 1948 at the Pescara Circuit and the Grand Prix of Naples, where it was driven to a win by Luigi Villoresi. The engine was modified to 1342 cc form (with 90 PS (66 kW; 89 hp) at 5500 rpm) in 1949.
In 1950, a new DOHC (MT4-2AD) raised power (to a maximum of 100 PS (74 kW; 99 hp) at 6300 rpm), and in 1953 the engine was enlarged to 1453 cc (110 PS (81 kW; 108 hp) at 6200 rpm). A twin spark with 1491 cc (120 PS (88 kW; 118 hp) at 6300 rpm) was later used in the O.S.C.A. TN of 1955.
These automobiles were mainly barchettas, but a few were built with more luxurious berlinetta bodies by Pietro Frua, Michelotti, and Vignale. A Vignale was run in the 1500 cc class at the 1953 24 Hours of Le Mans.
The 1954 12 Hours of Sebring was won by drivers Stirling Moss and Bill Lloyd in an O.S.C.A. MT4  as part of the Briggs Cunningham Team.
From 1951 to 1962, automobiles or engines made by O.S.C.A. also were entered in some Formula One and Formula Two events although they mainly built small sports cars of which some were designed by Pietro Frua. In the World Sportscar Championship OSCA vehicles ranked 10th (1953), 4th (1954), 6th (1957), 5th (1958) and 4th (1961).
The 750cc 70 hp (52 kW) type S 187 was introduced in 1956. Weighing 730 kg (1,609 lb), this car had a top speed of 116 mph (187 km/h). In 1959 Jim Eichenlaub won the American H-Mod Title with this OSCA S 187. Operating on a shoestring budget, Eichenlaub often slept in his tow car because there was no money for a motel. However he won his first race at Pensacola in April 1959.
The Formula Junior (FJ) used a Fiat engine of 1089 cc, saw wins by Colin Davis and Berardo Taraschi (1959).
In 1963 the brothers sold the company to Count Domenico Agusta, owner of MV Agusta, They did design work for Agusta until 1966. One of their final designs was a desmodromic four cylinder engine. It ended operations in 1967.
Nel 1937 i fratelli Ettore, Ernesto e Bindo avevano ceduto la loro fabbrica (La Officine Alfieri Maserati) ad Adolfo ed Omar Orsi, proprietari di una acciaieria e fabbrica di utensili. Il contratto di cessione prevedeva una consulenza decennale per i fratelli Maserati, cessata la quale decisero di fondare (1947) una propria officina per la produzione di automobili da competizione di piccola cilindrata: la OSCA.
Il primo modello prodotto dalla Casa di San Lazzaro fu la barchetta MT4 del 1948, spinta da un motore bialbero di 1092 cm3 da 72cv e destinata alle gare della categoria 1,1 litri.
La MT4 vinse il Gran Premio di Napoli del '48, guidata da Luigi Villoresi e conquisto parecchie affermazioni nella classe di cilindrata, condotta da Ada Pace, tra le quali una prestigiosa vittoria alla Targa Florio.
Negli anni successivi seguirono evoluzioni del bialbero con cilindrate di 1392cc (92cv), 1453cc (110cv), 1491cc (120cv) e 1568cc (140cv).
Dalle vetture da competizione Frua, Michelotti, Zagato, Fissore e Vignale derivarono eleganti e sportive coupé a 2 posti, come la 1600 GT appunto di Fissore.
L'ambizione di partecipare al campionato mondiale sport e alla Mille Miglia, portò alla nascita della MT4 equipaggiata con un motore 2 litri, bialbero a distribuzione desmodromica, da 165 cv. Questa vettura, guidata da Stirling Moss, aggiunse al palmares della OSCA la vittoria nella prestigiosa 12 Ore di Sebring.
I fratelli Maserati, ormai anziani, cedettero l'attività alla MV Agusta alla fine del 1964. Nel 1967 la OSCA chiuse i battenti.
I motori bialbero Osca, di 1491cm3 prima e 1568cm3 poi, andarono ad equipaggiare, in versione depotenziata a 90 e 100cv, modelli di più ampia diffusione, come le Fiat 1500 S (1959-1963) e 1600 S (1963-1966).