Across the United States, the rules for checking tailpipe pollution are quietly shifting, even as climate targets grow more ambitious and electric vehicles grab headlines. States are carving out ...

Although there has been increased attention paid to electric vehicles in recent years, that doesn't mean the regulations for gas guzzlers have been relaxed. Both automobiles and motorcycles still need ...

SMOG checks or emission tests exist due to the U.S. Environmental Protection Agency's (EPA) regulation on passenger vehicles. Each state sets limits of nitrogen oxides (NOx) from emitting past certain ...