M40

M40 is a designation applied to multiple, unrelated subjects across different domains. As a result, the meaning of M40 depends on context.

Messier 40 (M40) is a double star in the constellation Ursa Major. It was included in Charles Messier’s catalog and is notable for being a pair of stars rather than a nebula or galaxy, making it an unusual entry in the catalog.

The M40 motorway is a major road in England, linking London with Birmingham. It runs through the Chiltern Hills and Oxfordshire, serving as a key cross-country trunk route.

In automotive engineering, M40 refers to a BMW inline-four petrol engine family produced during the late 1980s and 1990s. The engines powered a range of BMW models and are noted for their balance of performance and efficiency.

In United States military usage, M40 has designated several sniper rifles and optical systems. The M40 rifle, deployed by the U.S. Marine Corps, is among the well-known examples associated with this designation.