The interior of the car is not your property. It has nothing to do with smuggling. Smuggling is an illegal activity. Owning a car is not. It's like owning a parking lot. The owner gets to decide if he wants the car parked there, or not. That's the full extent of his property right.
To bring in or take out illicitly or by stealth.
If I tell you that you are not allowed to bring porn to your place of work, and you sneak porn in, then claim that I have no right to search you because I want to make sure that you're not bringing porn into the workplace, you are claiming the right to smuggle; A.K.A. illicitly ringing something banned into the workplace.