Straight-eight engine
The straight-8 is a smooth running engine. This made it popular in luxury and racing cars of the past. The length of the engine required a long engine compartment. This makes the basic design unacceptable in modern vehicles. The design has been replaced almost completely by the shorter and sturdier V8 engine. Mercedes and BMW made straight-8 aircraft engines during World War I. The engine for aircraft use provided good aerodynamics.