In 1906, it produced, using the Auto-Mixte patents of Belgian Henri Pieper, a petrol-electric vehicle and on 23 May 1906 registered Gearless Motor Omnibus Co. Limited.[131] It was too heavy. Following the introduction of Daimler-Knight sleeve-valve engines re-designed for Daimler by Dr Frederick Lanchester Lanchester also refined the Gearless design and it re-emerged in 1910 as the KPL (Knight-Pieper-Lanchester) omnibus,[132] an advanced integral petrol electric hybrid.