Vehicle Rules

In addition to rules regarding modifications, cars must pass a series of tests and adhere to certain rules in order to be allowed on the road. FindLaw's Vehicle Rules section provides each state's vehicle registration information and emissions standards and testing. You can also find information about driver's licenses in this section since cars and driver's licenses are closely related.

Vehicle Registration

Each state requires cars to be registered with the state motor vehicle department. Registration of a car involves various fees and deadlines. Many states, like California, require that a person even register a non-operating vehicle. However, the fee to register a non-operating vehicle is usually lower than the fee for a vehicle that will be driven. Generally, the car's registration must be renewed each year, but this will vary from state to state. A car must also be re-registered when it changes owners. It's a good idea to keep the registration in the car because license and registration are the items that a police officer asks for when he or she pulls a driver over.

Emission Standards and Testing

Every state has standards when it comes to cars' emissions. These standards exist so that states can limit the amount of air pollution caused by cars. States notify the car owner that his or her car is due for emission testing, which is often referred to as a smog test. Some states, such as California, notify a car owner that his or her car is due for a smog check when the state sends the registration renewal. If your car requires a smog check, its registration will not be renewed until your car is tested and it passes the smog test. States have their own timelines for how often a car must be tested, but generally the older a car gets, the more often the car must be tested. Some states also require that the emission testing be done at state-approved testing centers.