In the early 20th century, NZR began experiments with railcars as an option to replace unprofitable regional locomotive-hauled carriage expresses and to provide efficient passenger service on rural branch lines that were served solely by slow mixed trains that carried both goods and passengers.

Such mixed trains had slow schedules as they had to load and unload freight regularly, making their stops longer than passenger service would normally require.

[1] Built in 1926 by Clayton Carriage and Wagon of Lincoln, England and assembled at NZR's Petone Workshops, the railcar could seat up to 52 people and its steam boiler could generate a pressure of 275 psi.

It could be driven from either end and was capable of hauling a wagon or two of freight, and its airy, open design proved popular with passengers.

Before it even commenced revenue operations, a heavier firebox and larger boiler had to be installed, and its poor reliability necessitated regular repairs.