What are the reasons for the smell of engine exhaust inside the car?

[MartinAnn]

Car inside has the smell of engine exhaust reasons are: the car's air-fuel mixture is too rich, the vehicle has turned on the external circulation mode during driving, and the throttle has excessive carbon deposits. An engine is a machine that can convert other forms of energy into mechanical energy. The first external combustion engine was invented by R. Stirling in the UK (Scotland) and later improved by Watt into a steam engine. Engines can be used as power generation devices or refer to the entire machine including the power unit (such as gasoline engines, aircraft engines). Their types include internal combustion engines (such as gasoline engines), external combustion engines (such as Stirling engines, steam engines), gas turbines (for racing cars), and electric motors.