The biggest difference between L3 and L4 engines lies in the number of cylinders. The L3 is a three-cylinder engine, which is simpler in structure, more compact, and lighter in weight, while the L4 is a four-cylinder engine with a relatively more complex structure. Additionally, the three-cylinder engine has less pumping loss. Theoretically, with one fewer cylinder, the engine produces less power, and the three-cylinder engine tends to have a relatively shorter lifespan. Moreover, the three-cylinder engine has one fewer piston, one fewer connecting rod, one fewer set of intake and exhaust valves, one fewer spark plug, one fewer ignition coil, one fewer fuel injector, one fewer intake manifold, and one fewer exhaust manifold compared to the four-cylinder engine. Automotive engines are generally composed of multiple cylinders, with common arrangements including inline (L-type), horizontally opposed, and V-type. In some luxury cars, a W-type arrangement may also be found, though it is relatively rare. Therefore, the "L" in L3/L4 represents the inline arrangement of the engine. L3 engines typically have smaller displacements, mostly around 1.2L or lower. Due to the inherent disadvantages of three-cylinder engines (poor NVH performance), brands like BMW and Dongfeng Peugeot in China have models equipped with three-cylinder engines for sale, including some microcars with displacements ranging from 0.8L to 1.0L, which mostly adopt the L3 configuration. L4 engines are very common and are found in most vehicles on the market. Their displacements typically range from 1.4L to 2.0L, making them one of the most mainstream engine configurations.
