I'm not sure, the information on this page leads me to believe that they could not search it without probable cause or you were already arrested for a crime.
jernlaw.com
If The Police Want To Search You, Your Home or Your Car:
You have the right to be free from unreasonable searches and seizures and, generally, police need a search warrant to search you or your belongings. Sometimes, police can search without a warrant. These situations include when:
1) You give your consent to be searched, but you do not have to consent to a search. You may tell the police politely and clearly that you object to their searching.
2) The police have probable cause. This means that the police must have trustworthy information that would lead a reasonable person to think it is probable that the search will uncover evidence of a crime or contraband.
3) Police conduct a search of the person and
the areas within that person's immediate control, including the passenger compartment of a car, following a valid arrest.
4) Search is motivated by an emergency situation.
Your car can be searched without a warrant so long as the police have probable cause or the search takes place after a valid arrest or the driver is arrested and both driver and car are taken to the police station. The police can also seize any objects appearing to be weapons or anything in plain view, even if it is inside your car or home.