I am not a CA lawyer and am not competent to talk about CA law or procedure but why would you want to be a passenger in a car (or even associate with for that matter) with someone whom you know has an active arrest warrant? Did I read your question wrong or did you not say that you have already once been arrested "by association"? Did you enjoy that experience so much that you wish to repeat?
The answer to your question is that, as a citizen, you have the right to be harassed by over-zealous law enforcement officers who, quite predictably, will almost certainly engage in questionable behavior because of your poor choice in associates.
Being with someone who has a warrant is not a crime but it is an invitation for abuse at the hands of law enforcement. I suggest you drop "the driver" like a hot potato (or at least don't ride around with her/him) and get yourself some new associates.
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Police will undoubtedly ask you for ID. I would show it to them. Lets assume they did nothing else. Are you riding with this person because you don't have a license? If so, and if the police stop the car and arrest the driver, you will be stranded. Depending on the nature of the charges for which the driver is on probation, they may have reason to believe that he is armed and may believe you are armed as well and pat you down for their own safety. If the feel a weapon or feel something that plainly feels like a package of controlled substance they have the authority to seize to examine it to see if it is a controlled substance. If they are going to give you a ride because you can't drive the car, they will pat you down for there own safety before they put you in the police vehicle. If any of this concerns you in the least, you should not accept rides from this person.
Show them your ID and give them your name and then shut up! You can "practice your rights" by saying "on the advice of counsel, I assert my Fifth Amendment right to remain silent, sir." And then remain silent.
If anyone from the car is arrested, the entire passenger compartment (including any containers, even if they don't belong to the arrested person) are subject to search.
You can always exercise your rights by not giving information to law enforcement beyond what you're required to give. You never have to consent to a search of your person or belongings. If they have probable cause to search and/or a recognized exception to the need for a warrant, they're going to search. Firmly, but politely decline the search, but do not physically resist. The time to fight about whether the search was lawful or not is not on the side of the road, but in court.
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