The original design featured 'air-smoothed' bodywork, which was very much the fashion at the time. The rounded lines of the first examples built led to their nickname: "flying banana". The preserved W4W is an example of the original, rounded body shape. Later examples, such as No. 22 (pictured), had much more angular (and practical) bodywork, yet the nickname persisted for these too. An odd feature of these units was the fitting of steam heating to them, which had the power to heat the railcar and another two to three coaches.An unusual feature was the external Cardan Shaft drive from the gearbox on the rear of a horizontally-mounted engine to road-vehicle style reduction boxes outboard of the two axles on one bogie. Later units had two such engine and drive combinations placed on opposite sides.Railcars 19-20 were fitted with a separate high-low ratio gearbox on the final drive side of the gearbox. This allowed a top speed of about 60-70 mph in high and about 40-45 in low. Railcar W20W retains this in preservation.
Below is a full list of GWR railcars:
Three of the GWR railcars have survived into preservation, as follows: