Daimler started testing the "Fluidrive" system in a bus chassis in 1928.[96] This system, patented by Harold Sinclair in 1926, applied Hermann Föttinger's fluid flywheel to replace the clutch in the transmission systems of road vehicles.[97][98] Daimler was initially interested in the fluid flywheel for use in commercial vehicles, but Martin decided to develop the system for use in passenger cars as well. Martin and Pomeroy originally intended to use the fluid flywheel with a conventional gearbox. Their consultant, Frederick Lanchester, warned them that putting a car with that combination on the market would be "a terribly big gambling risk,"[96] and an accident in March 1929 where a Double-Six 30 with a prototype transmission damaged a garage in Devon after Pomeroy left it idling while in gear may have shown the nature of this risk.[96] By October 1930, when Daimler introduced the fluid flywheel on their new Light Double-Six for an extra £50, it was used with the self changing gearbox developed by W. G. Wilson.[99][100] Martin and the Daimler Company patented their refinements to Sinclair's system in 1930.[98]