| Name | Description | Year Started | Year Ended |
| AC | British car manufacturer of London/Surrey/Glasgow | 1908 | |
| ACF | American commerical vehicle manufacturer of Detroit and Philadelphia | 1926 | 1953 |
| Associated Daimler | British commercial vehicle manufacturer of Walthamstow and Southall. Joint company formed by Daimler and AEC. | 1926 | 1928 |
| AEC | British commercial vehicle manufacturer of London/ Southall, Middlesex | 1912 | |
| AJS | British vehicle manufacturer of Wolverhampton | 1909 | 1931 |
| Albion | British commercial vehiocle manufacturer (and car maker until 1913) of Glasgow | 1900 | 1972 |
| ALFA Alfa Romeo | Italian vehicle manufacturer of Milan | 1910 | |
| Allard | British car manufacturer of London | 1937 | 1960 |
| Alldays | British vehicle manufacturer of Birmingham | 1898 | 1918 |
| Alvis | British vehicle manufacturer of Coventry | 1919 | 1967 |
| Amedee Bollee | French car manufacturer of Le Mans | 1885 | 1921 |
| American Motors | American vehicle manufacturers of Kenosha, Wisconsin | 1968 | 1987 |
| Amercian LaFrance | American fire engine manufacturer of Elmira and Ladson | 1910 | |
| American Coleman | American truck manufacturer of Littleton Colorado | 1925 | |
| Amilcar | French car manufacturer of St Denis/Boulogne-sur-Seine | 1921 | 1939 |
| Angus Sanderson | British car manufacturer of Birtley and Hendon | 1919 | 1927 |
| Arab | British car manufacturer of Letchworth, Hertfordshire | 1926 | 1928 |
| Argyll | British vehicle manufacturer of Glasgow | 1899 | 1928 |
| Ariel | British manufacturer of vehicles of Birmingham | 1897 | 1926 |
| Aries | French manufacturer of cars and trucks | 1903 | 1938 |
| Armstrong Siddeley | British vehicle manufacturers of Coventry | 1919 | 1960 |
| Armstrong-Saurer | British commercial vehicle manufacturer of Newcastle-Upo | 1931 | 1937 |
| Armstrong-Whitworth | merger with Siddeley-Deasy | 1906 | 1915 |
| Arnold | British car manufacturer of East Peckham Kent | 1896 | 1898 |
| Arrol-Johnston | British vehicle manufacturers of Glasgow/Dumfries | 1895 | 1931 |
| Ashok Leyland | Indian commercial vehicle manufacturer of Enore, Madras | 1948 | |
| Aster | British Car Manufacturer. Cars badged Arrol Aster from 1927 to 1930. | 1922 | 1927 |
| Aston Martin | British car manufacturer of Gaydon, Warwickshire | 1921 | |
| Atkinson | British manufacturer of commercial vehicles of Preston, Lancashire | 1925 | 1975 |
| Audi | German car manufacturer of Ingolstadt | 1910 | |
| Austin | British vehicle manufacturer and marque of Longbridg | 1905 | 1990 |
| Austro Daimler | Austrian vehicle manufacturer of Wiener Neustadt | 1899 | 1935 |
| Autocar | American manufacturer of commerical vehicles. Volvo acquired White and dropped the Autocar name in the 1980s. | 1908 | 1981 |
| Auto Union | German manufacturer of cars. Formed in 1958 from amalgamation of Audi, Wanderer, DKW, and Horch. Name also used for German GP racing cars in the 1930s. | 1958 | 1969 |
| Avro | British manufacturer of micro cars. A division of the Avro aeroplane company. | 1919 | 1920 |
| AWD | British commercial vehicle manufacturer of Dunstable. Management buyout of Bedford trucks operation. | 1988 | 1992 |