Can the police search my car without a warrant?

The automobile exception permits a warrantless search of a vehicle where an officer has probable cause to believe it contains evidence of a crime. The reasoning is mobility — a car can be driven away while a warrant is sought.

That doesn't make every vehicle search lawful. The question shifts to whether probable cause actually existed, and probable cause is a specific standard rather than an officer's judgment call. It requires facts making it substantially likely that evidence of a crime will be found.

Other routes exist. Consent. A search incident to arrest, which is narrower than people assume. An inventory search after a lawful impound, which has its own requirements. A protective sweep of the passenger compartment where there's reason to believe a weapon is present.

Each of those has boundaries, and searches routinely exceed them. The question in any given case is which justification the officer relied on and whether the facts supported it.