| UN Rule No. 1 Environmental Protection | Uniform provisions for periodical technical inspections of wheeled vehicles with regard to the protection of the environment Requirements for inspections of medium and heavy passenger and commercial vehicles with regard primarily to exhaust and noise emissions. The World Forum has agreed to consider expanding the scope of UN Rule No. 1 to include light vehicles. Environmental Protection Vehicle Inspections: Environmental Protection UN Rule No. 1 Rule No. 1 |
| UN Rule No. 2 Roadworthiness | Uniform provisions for periodical technical inspections of wheeled vehicles with regard to their roadworthiness UN Rule No. 2 establishes uniform conditions for periodical administrative procedures by which an authorized vehicle inspection center declares, after carrying out the required verifications, that the vehicle submitted conforms to safety requirements established by this Rule. This rule applies to M<sub>2</sub>, M<sub>3</sub>, N<sub>2</sub> and N<sub>3</sub> vehicles and O<sub>3</sub> and O<sub>4</sub> trailers used in international transport whose permissible maximum mass exceeds 3,500 kg, except for passenger vehicles having not more than eight seats in addition to the driver's seat. Roadworthiness Vehicle Inspections: Roadworthiness UN Rule No. 2 Rule No. 2 |
| UN Rule No. 3 CNG/LNG Vehicle Inspections | Proposals for new Rule on Periodical Technical Inspections of motor vehicles using Compressed Natural Gas (CNG) and/or Liquefied Natural Gas (LNG) in their propulsion system CNG/LNG Vehicle Inspections Technical Inspection of Vehicles powered by Natural Gas UN Rule No. 3 Rule No. 3 |
| UN Rule No. 4 Electrified vehicle safety PTI | Electrified vehicle safety PTI Safety inspection requirements for hybrid and electric vehicles UN Rule No. 4 Rule No. 4 |