In Byrd v. United States the Supreme Court held unanimously that the driver of a rental car generally has a reasonable expectation of privacy in the rental car even if he or she isn’t listed as an authorized driver on the rental agreement.
A state trooper pulled Terrance Byrd over for a possible traffic infraction. Byrd’s name was not on the rental agreement. He told the officer a friend had rented it. Officers searched the car and found 49 bricks of cocaine and body armor.
While the Fourth Amendment prohibits warrantless searches, generally probable cause a crime has been committed is enough to search a car. To claim a violation of Fourth Amendment rights a defendant must have a “legitimate expectation of privacy in the premises” searched.