"(b) If a vehicle is being driven at a speed less than the normal speed of traffic moving in the same direction at such time, and is not being driven in the right-hand lane for traffic or as close as practicable to the right-hand edge or curb, it shall constitute prima facie evidence that the driver is operating the vehicle in violation of subdivision (a) of this section."

http://www.leginfo.ca.gov/cgi-bin/displaycode?section=veh&gr...

Says nothing about limited-access divided highways.