The GWR petrol-electric railcar was a 4-wheel motorised coach purchased by the GWR in 1911 from British Thomson-Houston, who designed it and supplied the electrical fittings. It was powered by a Maudslay petrol engine driving a dynamo which supplied two electric motors, one on each axle. It was provided with a driving position at both ends, and could carry 44 passengers at over . It was numbered 100.
It was in use on the GWR until October 1919, when it was sold to Lever Brothers, who ran it at Port Sunlight until 1923.