John Joyce, Bowin Cars founder, was the Lotus chief designer and was assisted by Dave Baldwin. They started with a clean sheet of paper. The chassis was a welded tubular steel space frame. The racing classes of this period imposed minimum weight requirements, so steel could be used in place of aluminium without a weight penalty. The most notable feature of the new design was the extensive use of stressed steel panels in the bulkheads, welded steel around the footwell and the instrument panel, a welded sheet of steel surrounding the driver's shoulder, and a double-sided steel cradle surrounding the gearbox. Floors were also welded for additional stiffness.
Another clever design feature of the Type 41 was the use of a rear bulkhead as an oil overflow collector. Even the front oil tank had its overflow routed through a labyrinthine path using chassis tubes all the way to the back.