Commercial vehicles based on the car chassis were also built from 1922 and became an increasingly important part of the company's output.

In 1923 coil ignition and electric starting were added and the four-seater "Long Four" was introduced in tourer form priced from £245 followed in 1925 by a closed saloon model, the previous short-chassis two-seater continuing in production.

When production restarted after the Second World War, the twin-cylinder engine was dropped from the range of new cars, but continued in 1005 cc form to the end of production in the commercial vehicles, now comprising a light lorry, the Bradford van, two versions of an estate car called the Utility, and chassis front-ends and kits for outside coachbuilders, many abroad.

The new cars were a complete change from what had gone before with the streamlined Jowett Javelin designed by a team led by Gerald Palmer.

In 1950 the Javelin was joined by the Jowett Jupiter sports car with a chassis designed by Eberan von Eberhorst who had worked for Auto Union.

[6] Poor business strategy and direction, and over-confidence, were the financially sound company's downfall and, even after the engine and gearbox problems were solved, the Idle plant was never able to build, nor – during 1952 – was the distribution network able to sell, the expected volume.

Collapse of the arrangements for the supply of bodies led to suspension of Javelin production in 1953, together with the by now outdated Bradford, though tooling had been completed for new models.

In the resulting scramble for production facilities, Ford bought Briggs, whose new Doncaster plant built the unitary construction bodies and fully trimmed them for Jowett Javelin cars and Bradford vans.

Jopling, who at the time was also a senior employee with Blackburn Aircraft, informed Jowett shareholders at their Annual General Meeting that difficulties had arisen over the future supply of car bodies.

Negotiations were proceeding, but an interruption in delivery of completed vehicles appeared likely to occur in the closing months of that year.

[6] In mid-September the board advised shareholders that the forecast break in production was unavoidable, and that it might prove to be of considerable duration.

It also advised that the difficulty in arranging supplies of new bodies would unfortunately postpone the production of the new range of commercial vehicles, and the estate car, which were fully tooled-up.

In July 1954 it was announced that Jowett Cars Limited would sell its main factory at Idle to International Harvester, excluding plant and equipment needed for the service and spares departments.

A note was added by The Times that Jowett Cars had run into difficulties the previous year (1953), following the acquisition of the motor body suppliers Fisher and Ludlow by BMC,[10] completed in September 1953.

"It is now stated that since the company ceased manufacturing Javelin and Bradford vehicles it has not been found possible to keep the main factory operating at an economic level."

[11] At the 35th Annual General Meeting in August 1954, the chairman advised the profound regret of the board and all associated with the company, including the users of the some 65,000 vehicles which had been made since 1946, for their joint circumstances.