Wash. Rev. Code § 46.61.535
It shall be unlawful for any manufacturer, dealer, distributor, or any person, firm, or corporation to publish or advertise or offer for publication or advertisement, or to consent or cause to be published or advertised, the time consumed or speed attained by a vehicle between given points or over given or designated distances upon any public highways of this state when such published or advertised time consumed or speed attained shall indicate an average rate of speed between given points or over a given or designated distance in excess of the maximum rate of speed allowed between such points or at a rate of speed which would constitute reckless driving between such points. Violation of any of the provisions of this section shall be prima facie evidence of reckless driving and shall subject such person, firm, or corporation to the penalties in such cases provided.
RCW 46.61.535
Effective date-Severability-1979 ex.s. c 136: See notes following RCW 46.63.010.