M40 motorway, a motorway in England

M40 rifle, a sniper rifle

M40 GMC, a United States self-propelled artillery vehicle

M40 recoilless rifle, an anti-tank gun

M40 (field protective mask), a United States military gas mask

M-40 (Michigan highway), a state highway in Michigan

Messier 40 (M40), a double star in the constellation Ursa Major

BMW M40, an automobile piston engine

Volvo M40 transmission, an automobile transmission