35 Miss. Code R. § 4-05-09-101
Self service, coin operated car washes where the customer deposits money for the car wash are exempt. This includes self-service bays where the customer washes his own vehicle or where the vehicle is washed by automatic wash equipment. Automatic car wash bays located at facilities such as convenience stores, gas stations and oil change facilities are considered to be self-service, coin operated car washes and are exempt. In order for a car wash facility to be exempt, the facilities' employees cannot provide any assistance in the washing, drying or detailing of the automobile. Manual car washes, detail shops, and those with a mixture of manual and automatic services are subject to tax at the regular retail rate.
35 Miss. Code. R. § 4-05-09-101