C.R.S. § 44-20-302: Sunday closing.

No person, firm, or corporation, whether owner, proprietor, agent, or employee, shall keep open, operate, or assist in keeping open or operating any place or premises or residences, whether open or closed, for the purpose of selling, bartering, or exchanging or offering for sale, barter, or exchange any motor vehicle, whether new, used, or secondhand, on the first day of the week commonly called Sunday. This part 3 shall not apply to the opening of an establishment or place of business on the first day of the week for other purposes, such as the sale of petroleum products, tires, or automobile accessories, or for the purpose of operating and conducting a motor vehicle repair shop, or for the purpose of supplying such services as towing or wrecking. The provisions of this part 3 shall not apply to the opening of an establishment or place of business on the first day of the week for the purpose of selling, bartering, or exchanging or offering for sale, barter, or exchange any boat, boat trailer, snowmobile, or snowmobile trailer.