The Bluebird railcars were built to provide modern air-conditioned services on the country passenger rail system where the patronage did not warrant the use of locomotive hauled passenger trains, and to replace the ageing fleet of Brill railcars introduced in 1924.

In December 1948, tenders were called for 30 sets of engines, gearboxes, electrical assemblies and compressors.

Cotal subsequently ceased trading in April 1954 with only six gearboxes having been delivered, so an alternative source was found.

[6] They operated services on the broad-gauge network from Adelaide to Burra, Gladstone, Moonta, Morgan, Mount Gambier, Nuriootpa, South Australia, Port Pirie, Tailem Bend, Terowie (extended to Peterborough in 1970) and Victor Harbor.

[12][13] By 1985, ten Bluebirds had been fitted with standard-gauge bogies for use on services to Port Pirie, Whyalla and Broken Hill.

[17][18] In 1989, shortly before all South Australian country passenger services were withdrawn, the 100 class trailers began to be used as sitting carriages on the Indian Pacific and The Overland.

The venture ceased in April 2003, after which the railcars were stored at the National Railway Museum, Port Adelaide.

[35] Starting in the 2000s, a majority of the railcars were converted to crew cars at Islington Railway Workshops for private freight operators.