Colorado Revised Statutes Title 42. Vehicles and Traffic § 42-12-404. Emissions

(1) Except as provided in subsection (3) of this section, a motor vehicle of historic or special interest manufactured prior to the date emission controls were standard equipment on that particular make or model of vehicle is exempted from statutes requiring the inspection and use of such emission controls. A motor vehicle using emission controls as standard equipment at the time of manufacture must have such equipment in proper operating condition at all times when the vehicle is operated on or for highway purposes.

(2) A certification of emissions control that has been issued for a motor vehicle that is registered as a collector's item before September 1, 2009, and that is of model year 1976 or later is valid until the motor vehicle is sold or transferred.

(3) Except for a motor vehicle that was registered before September 1, 2009, and meets the requirements of subsection (2) of this section, to register or reregister a collector's item that is model year 1976 or newer, the owner must have a certificate of emission control issued under part 3 of article 4 of this title.