See also:

State emission testing (U.S. only)
WARNING Testing of an All-Wheel Drive vehicle must NEVER be performed on a single two-wheel dynamometer. Attempting to do so will result in uncontrolled vehicle movement and may cause an accident ...

For U.S.A.
The following information has been compiled according to Code of Federal Regulations “Title 49, Part 575”. ...

Unfastening the front seatbelt
Push the button on the buckle. Before closing the door, make sure that the belts are retracted properly to avoid catching the belt webbing in the door. ...