In the state of California, smog tests are required every two years for all vehicles, from cars to mobile homes. At STAR-certified Smog Center locations, licensed technicians help owners stay compliant and air friendly through a three-step process. It begins with a visual inspection of the vehicle for obvious emissions problems, followed by a functional exam and an evaluation. But what the process doesn't include is a sales pitch: since the facility is a test-only center, the staff doesn't try to sell owners on extra repairs, nor on gold watches conveniently located in a mechanic's trenchcoat.