Wash. Rev. Code § 46.76.010
It shall be unlawful for any person, firm, partnership, association, or corporation to engage in the business of delivering by the driveaway or towaway methods vehicles not his or her own and of a type required to be registered under the laws of this state, without procuring a transporter's license in accordance with the provisions of this chapter.
This shall not apply to motor freight carriers or operations regularly licensed under the provisions of chapter 81.80 RCW to haul such vehicles on trailers or semitrailers.
Driveaway or towaway methods means the delivery service rendered by a motor vehicle transporter wherein motor vehicles are driven singly or in combinations by the towbar, saddlemount or fullmount methods or any lawful combinations thereof, or where a truck or truck tractor draws or tows a semitrailer or trailer.
RCW 46.76.010