The first flat engine was built in 1897 by Karl Benz. Flat engines have been used in various aviation, motorcycle and automobile applications, and are now less common than straight engines (for engines with less than six cylinders) and V engines (for engines with six or more cylinders) in cars, but are much more common in aircraft, where straight engines are a rarity and V engines have become almost non-existent other than on historical types, and they have even replaced radial engines in many smaller installations.