Most states don't require smog tests for their vehicles, and those that do often have lax requirements. However, California is very strict about smog, and a lot of cars will fail CA's standards while passing in most other states. If you have to get a smog test, then you'll pay anywhere from $40 to $60 per test. It's important to find a mechanic that will offer a retest at a reduced price, or for free if you do the mechanic's suggested repairs through that particular repair garage before a retest. Otherwise, you could wind up paying a lot of extra money unnecessarily.