The majority of the Austin FX4 vehicles were painted in black. Production began in 1958 and continued through 1997. The FX4 was the successor to the Austin FX3 which was in production from 1948 through 1958. The FX4 was the first London taxi to enter production that had four doors.
The design for the FX was done by Austin in collaboration with Mann and Overton, the London taxi dealership that commissioned their production. The coachbuilder, Carbodies, built the body and assembled the cabs. The original design was by Austin's Eric Bailey and it was engineered for production by Carbodies' Jake Donaldson.
The FX4 had a separate chassis and an independent front suspension with dual-circuit hydraulic brakes. Powering the early examples was a 2178cc Austin diesel engine mated to a Borg-Warner automatic transmission. A manual gearbox became available as an option beginning in 1961.
For 1962, the Austin FX4 was powered by a 2199cc petrol engine, though most of the FX4 taxis were given diesel engines and, until the mid-1970s most had a manual transmission.
The 2178cc diesel engine was replaced by a 2520cc version in 1971. It worked well with automatic gearboxes and soon, most of the FX4's came with automatics. The petrol engine was no longer offered beginning in 1973.
After Carbodies' owner BSA collapsed in 1973, the were bought by Manganese Bronze Holdings, who continued the production of the FX4.