Final answer:
Vehicles needing emissions tests must get certified by a licensed station. The EPA tests a small number of new vehicle models, and manufacturers must report fuel economy data based on emissions tests. This data is used for the EPA's fuel economy standards.
Step-by-step explanation:
All vehicles requiring an emissions test should obtain an emissions inspection certification from a licensed emissions inspection station. It's interesting to note that the Environmental Protection Agency (EPA), contrary to public perception, conducts emissions testing on a relatively small sample of vehicles. With approximately 18 employees in their automobile-testing department located in Ann Arbor, Michigan, the EPA examines 200 to 250 vehicles annually—about 15 percent of new models.
Additionally, when it comes to fuel economy reporting, automobile manufacturers selling in the United States must provide EPA fuel economy test results. These results are derived from emissions data collected during the Clean Air Act certification tests, where the concentration of carbon in the exhaust is measured and calculated. Contrary to the rigorous testing some might expect, the EPA largely relies on the automakers' own submitted test results for the remaining 85 percent of new models, accepting them as accurate without independent verification. This means that only about a third of the vehicles tested by the EPA are chosen because they require specific scrutiny, and the rest are selected randomly.