The most important thing for you to understand about classic car emission control requirements is that each state can have significantly different emission control requirements. When it comes time to consider purchasing a classic car, you need to do some research about your state's vehicle registration emission control regulation. Does your state require you to have your classic car smog checked, starting from what year, and what modifications will you have to make to the car in order for it to pass your state's regulations.

Did you know? In the state of California, you do not need to (at this time) smog check a "classic" car. Beginning April 1, 2005, the 30-year rolling exemption has been repealed. Instead, vehicles 1975 model-year and older will be exempt. Therefore, 1976 model-year and newer vehicles will continue to be subject to biennial inspection indefinitely. http://www.smogcheck.ca.gov/stdhome.asp

In the state of Arizona: Unless specifically exempted, all 1967 and newer vehicles (including diesels) that are registered in the metro Phoenix (Area A) or Tucson (Area B) emission test areas must receive an emissions inspection no more than 90 days prior to registration. http://www.azdeq.gov/environ/air/vei/tested.html

As you can see from the above two samples: What a big smog check difference.

Check out your state's classic car smog check requirement.

Links:

www.dmv.org