Originally Posted by Retro
They will search your vehicle if they arrest you.
They can only search your vehicle with your consent prior to that or with a warrant.
They MAY search your vehicle anyway, but as long as you do not give consent, and better yet tell them that you do not consent to a search, if they find anything you shouldn't have your lawyer will file a motion to dismiss on Fourth Amendment grounds.
With PC, the vehicle can be searched with or without your consent and without a warrant.