Answer :
Answer: The first nationwide US light duty vehicle emission standards were implemented in 1968, and subsequently reviewed every couple of years. New standards were referred to by the effective model year of the regulation from 1968 to 1987
Answer: The first nationwide US light duty vehicle emission standards were implemented in 1968, and subsequently reviewed every couple of years. New standards were referred to by the effective model year of the regulation from 1968 to 1987