What is the effect of a police order to drive an automobile to a service station?

Appellants' reliance on People v. Gonsoulin (1971) 19 Cal.App.3d 270, 96 Cal.Rptr. 548, is misplaced. There, a police officer stopped an automobile because the rear license plate was smudged, obscuring the state of origin and some of the numbers. After investigation of the smudging and verification of the vehicle's ownership and the driver's identity, the officer 'requested' the driver to turn around and drive some seven miles back in the direction from which he had come to a service station to enable the police to investigate the status of a credit card found in the driver's wallet. On reaching the service station the police made a search of the automobile and its occupants, found narcotics and arrested the occupants. We reversed, holding that the order to drive the automobile to the service station amounted to an arrest without probable cause and that the evidence of narcotics was arrived at by exploitation of that illegal detention.