Commer was a British manufacturer of commercial vehicles which existed from 1905 until 1979. The company started as the Commercial Car Company (CCC) in Lavender Hill, South London where it produced its first truck in 1907.

The QX range of lorries was introduced in 1948, powered by a six-cylinder petrol engine. Customers attracted to the benefits of running diesel rather than petrol engines, lead to the firm looking at their options for introducing an oil-burner to the range. 1954 saw the introduction of their reply to this demand, the TS3-powered QX, powered by a unit originally designed by Tilling-Stevens (hence the "TS") and produced at their factory in Maidstone, the firm - like Commer - by now part of the Rootes Group empire.

From its 3.26 litre capacity it produced a healthy 105bhp, its compact layout enabling Commer to accommodate it beneath the QX's cab floor. The two-stroke engine's configuration was anything but conventional. It employed three horizontal cylinders, each of which housed a pair of pistons. Contributing to the TS3's distinctive engine note was a Wade Roots-type supercharger, driven by a shaft that, on occasion, would break - perhaps the type's main Achilles' heel. Overall though it was a tough and dependable unit, and one that served the Rootes Group well for the life of its production. Its distinctive sound led to the nickname 'Commer Knocker'

The famous Ecurie Ecosse racing car transporter is built on a Commer QX bus chassis.