Karl Benz’s first automobile, which was a commercial success, sparked interest in lightweight engines. For light automobiles, the gasoline internal combustion engine with a four-stroke Otto cycle has been most successful, while diesel engines, which are more efficient, are used in trucks and buses. However, even for relatively small automobiles, turbo diesel engines have recently gained popularity, particularly outside of the United States.

Karl Benz received a patent for the first engine with horizontally opposed pistons in 1896. His design resulted in an engine in which the corresponding pistons automatically balance each other out in terms of their own momentum by moving horizontally through cylinders and simultaneously reaching the top dead center.

Because of their shape and low profile, engines of this design are frequently referred to as flat engines. They were utilized in propeller aircraft engines, the Citron 2CV, some Porsche and Subaru automobiles, numerous BMW and Honda motorcycles, and the Volkswagen Beetle.

The development of engine control systems, which include electronic fuel injection and onboard computers that manage the engine, is one reason why automobiles continue to use the internal combustion engine. Both turbocharging and supercharging employ forced air induction to improve engine efficiency and power output. Smaller diesel engines have been subjected to similar modifications, which have resulted in almost identical power characteristics to those of gasoline engines. This is particularly obvious with the prominence of more modest diesel motor moved vehicles in Europe.