Doors off in
Colorado.

The mirror rule in Colorado

Colorado's mirror law (Colo. Rev. Stat. § 42-4-226) asks for a mirror that shows the road behind you; it doesn't specifically demand a side mirror. A clear interior rearview can meet that as written. Stack gear in the back, fog up a soft-top window, or tow something and you'll want outside mirrors. Most doors-off drivers run them anyway, because a Jeep's factory side mirrors leave with the doors.

“shall be equipped with a mirror or mirrors so located and so constructed as to reflect to the driver a free and unobstructed view of the highway for a distance of at least two hundred feet to the rear”

Source: Colo. Rev. Stat. § 42-4-226

Fenders and mud flaps

The splash-guard statute exempts passenger-carrying vehicles registered under § 42-3-306(2) and trucks with an empty weight of 10,000 lb or less. A keyword search of the equipment sections §§ 42-4-201 to -241 found no other fender rule for passenger cars. (Colo. Rev. Stat. § 42-4-1407.5)

Source: Colo. Rev. Stat. § 42-4-1407.5

Do you need doors at all?

We didn't find any Colorado statute that requires doors on a passenger vehicle or makes removing them an offense. The rules that matter are the equipment rules: mirrors first, then fenders and lighting.

§ 42-4-226(2) requires an exterior mirror on each side when a vehicle 'is not equipped with a rear window and rear side windows.' Read literally, that could cover a Wrangler/Gladiator with the top and rear glass removed, so with the top off you would need mirrors on both sides. This is our reading of the statute text, not a court ruling.