The police can search a car without consent.  The police had probable cause to search the car since the driver was impaired.  The police can search a car without a search warrant when there is probable cause (reasonable belief that criminal activity is afoot) because by the time the police return with a warrant, the car may be gone.  The police don't need a warrant for a search incident to an arrest. Your argument about the police searching the car without consent will be rejected by the court.