Vehicles can be categorized in numerous ways. For example, by means of the body style and the "level of commonality in vehicle construction as defined by number of doors and roof treatment (e.g., sedan, convertible, fastback, hatchback) and number of seats" that require seat belts to meet safety regulations.
Regulatory agencies may also establish a vehicle classification system for determining a tax amount. In the United Kingdom, a vehicle is taxed according to the vehicle's construction, engine, weight, type of fuel and emissions, as well as the purpose for which it is used.
Other jurisdictions may determine vehicle tax based upon environmental principles, such as the user pays principle.
In another example, certain cities in the United States in the 1920s chose to exempt electric-powered vehicles because officials believed those vehicles did not cause "substantial wear upon the pavements."
Another standard for road vehicles of all types that is used internationally (except for Australia, India, and the U.S.), is ISO 3833-1977