After a difficult first year for Lotus in the 3 litre formula, Chapman went back to the drawing board and came up with a design that was both back to basics, and a leap ahead. Taking inspiration from earlier designs, particularly the Lotus 43 and Lotus 38 Indycar, the 49 was the first F1 car to be powered by the now-famous Ford Cosworth DFV engine after Chapman convinced Ford to build an F1 powerplant.
The 49 was an advanced design in Formula 1 because of its chassis configuration. The specially-designed engine became a stress-bearing structural member (seen first with the H16 engine in the Lotus 43 and BRM P83), bolted to the monocoque at one end and the suspension and gearbox at the other. Since then virtually all Formula 1 cars have been built this way.