In what circumstances will the police search the vehicle of a suspect who has been arrested for driving under the influence of a narcotic?

In contrast are those cases where there is reasonable cause to believe a crime has been committed, where a suspect has been arrested, and where there is rational ground to believe that evidence relating to the crime for which the suspect has been arrested may be found in the vehicle. Such is the situation in an arrest for drunk driving or for driving under the influence of a narcotic. (People v. Robinson, 62 Cal.2d 889, 894, 44 Cal.Rptr. 762, 402 P.2d 834.) At bench petitioner was arrested in or about his vehicle for being under the influence of a narcotic. Undoubtedly, the only reason he was not arrested for driving under the influence of a narcotic was that the arresting officer at the time of arrest could not be certain that petitioner had been the driver of the vehicle and not a passenger. But an arrest under either charge gives the police probable cause to search the vehicle for specific evidence of the offense for which the arrest has been made.