 Powered by an 1842 cc 4-cylinder overhead-valve Alvis engine, it had an aluminium body on an ash wood frame.As with other Alvis cars, the Firebird was built as a rolling chassis then sent to the coachbuilders Cross & Ellis, to be finished to the customer's requirements, so all Alvis Firebirds are different.The Firebird had an all-synchromesh gearbox, and the chassis was lubricated by grease nipples under the bonnet.