As already stated...If probable cause to search is present he can search your vehicle with or without your permission.If the officer asks to search the car, Just Say NO!!!
I personally carry nothing illegal and no officer is going to search my vehicle without a warrant.
A search warrant does not come into play.
Has anyone ever had to go through a secondary search at a Border Patrol checkpoint? They search hundreds of cars each day...
OMG where is their search warrant!!???