Because of the unavailability of certain car models, demand for grey market vehicles arose during the "Malaise era" in the late 1970s. Importing them into the US involved modifying or adding certain equipment, such as headlamps, sidemarker lights, bumpers, and a catalytic converter as required by the relevant regulations. The NHTSA and EPA would review the paperwork and then approve possession of the vehicle. It was also possible for these agencies to reject the application and order the automobile destroyed or re-exported The grey market provided an alternative method for Americans to acquire desirable vehicles, and still obtain certification.