BMW N40 is an inline four-cylinder naturally aspirated engine of the car manufacturer BMW with 16 valves. This engine model was developed for markets with special displacement taxation.  The N40 is parallel to the N42 developed and related to it. For example, the cylinder crankcase, including piston engines of this same design , as the cylinder bore of 84 mm is equal. The different displacements are generated by another stroke. Unlike the N42 has the N40 does not have the Valvetronic system. In the modification of the N42 to the N46 and the N40 was for N45 developed.