What is the efficiency of a car engine?

[KingAnn]

Below is the efficiency of a car engine: Limited by the Carnot cycle: The theoretical maximum efficiency of a gasoline engine is about 36%, and the efficiency of diesel engines is also not high. From the perspective of energy conversion: The conversion of electrical energy to kinetic energy has the highest efficiency, reaching up to 90%, and is affected by non-quasi-static processes (friction losses). Gasoline engine efficiency: Currently, the efficiency of gasoline engines is generally one-fourth to one-fifth that of electric motors, i.e., about 20%. Related descriptions are as follows: Effective torque: The torque output by the engine is called effective torque, which is the engine's torque. Effective power: The effective work output by the engine per unit time is called effective power, which is the engine's power, equal to the product of effective torque and crankshaft angular velocity.