RCW 46.04.465
RCW 46.04.465: Rental car.
(1) "Rental car" means a passenger car, as defined in RCW 46.04.382 , that is used solely by a rental car business for rental to others, without a driver provided by the rental car business, for periods of not more than thirty consecutive days. (2) "Rental car" does not include: (a) Vehicles rented or loaned to customers by automotive repair businesses while the customer's vehicle is under repair; (b) Vehicles licensed and operated as taxicabs.