Which statement is true regarding the functional test of gas caps for vehicles under the smog check inspection program?

The statement that all vehicles require a gas cap inspection regardless of age is accurate for the smog check inspection program. This requirement is in place because a properly functioning gas cap is crucial for preventing evaporative emissions, which can contribute significantly to air pollution. During the inspection, the gas cap is assessed for its ability to create a proper seal, ensuring that fuel vapors do not escape into the environment.

The smog check program emphasizes the importance of controlling emissions from all types of vehicles, hence the inclusion of this test for every vehicle. This approach helps to maintain air quality standards and promotes effective emission controls across the board, regardless of the model year of the vehicle. The functional test ensures that even older vehicles, which may not have advanced emission controls, are compliant with standards designed to protect the environment.