* Safety Standards: Cars must meet safety standards set by the National Highway Traffic Safety Administration (NHTSA). This includes things like seatbelts, airbags, brakes, lights, and emissions controls. A car that has been significantly modified to not meet these standards becomes illegal. For example, a car with severely rusted brakes or missing required safety equipment.
* Emissions Standards: Cars must meet Environmental Protection Agency (EPA) emissions standards. Cars that fail emissions testing are generally not street legal until they pass. Older cars, especially, may not meet modern standards.
* Registration and Insurance: All cars driven on public roads must be properly registered with the state and carry valid insurance. Driving an unregistered or uninsured car is illegal.
* Modifications: While some modifications are allowed, extensive alterations that violate safety or emissions regulations can make a car illegal. This includes things like modifying the engine to exceed noise or emissions limits, or making structural changes that compromise safety.
* Stolen Vehicles: Obviously, driving a stolen car is illegal.
In short, it's not about the *make and model* being illegal, but rather the car's *condition and compliance with regulations*. A perfectly legal car today can become illegal if it's severely damaged, modified improperly, or not properly registered and insured.
