What type of vehicles must perform a smog check every year instead of every two years?

Certain diesel vehicles that exceed a specific weight threshold are required to undergo smog checks annually rather than biennially. This policy is in place because these larger diesel engines generally produce higher levels of pollutants compared to lighter vehicles. Regular annual inspections help ensure that these vehicles meet emissions standards more frequently, contributing to improved air quality and compliance with regulatory requirements.

On the other hand, electric vehicles do not produce tailpipe emissions and are therefore exempt from smog checks. Gasoline vehicles typically follow a two-year inspection cycle unless they fall into categories requiring more frequent testing. Hybrid vehicles often align with the same regulations as gasoline vehicles, allowing them to adhere to the biennial testing schedule. Thus, the specific regulations for heavier diesel vehicles necessitate more stringent testing to monitor their emissions effectively.