What is the process by which a vehicle’s emissions are tested for compliance?

The process of testing a vehicle's emissions for compliance is known as emissions testing or inspection. This process involves measuring the pollutants emitted by a vehicle's exhaust system to determine whether they meet regulatory standards set by environmental authorities. Emissions testing is designed to ensure that vehicles are not contributing excessively to air pollution and that they operate within specified limits for harmful emissions such as carbon monoxide, hydrocarbons, and nitrogen oxides.

On the other hand, vehicle inspection typically covers a broader range of safety checks and may include various components of the vehicle, not solely focused on emissions. Fuel quality testing assesses the type and quality of fuel being used but does not directly measure exhaust emissions. Engine performance analysis focuses on how well the engine is operating but may not provide a direct assessment of emissions compliance. Thus, the specificity of emissions testing or inspection makes it the correct answer in this context.