 The engine itself was Coventry Climax's "FPF" straight-4, in a variety of sizes.Initially the cars were fitted with the 2-litre powerplant, but as Climax gradually stretched the FPF's capacity the Lotus 16 appeared with a 2.2, then finally a 2.5-litre, full Formula One engine specification.As in the 12, the engine's power was transmitted to the road through the rear wheels, via Lotus's own 5-speed sequential manual transaxle.