Yes, you can be arrested for any illegal items found in your car. However, in order to convict you of the crime of Possession of Marijuana, the government has to prove that you had knowledge the cannabis was in the car, and it was in an area that you could control. For example, if you are stopped by a police officer and your passenger has marijuana in his/her pocket, you cannot be charged with that.
A good idea would be that if you are getting into a car to make sure nobody has anything illegal on their person, in their pockets or in any bags or packages they are holding. The best defense to any crime is to not be there when it happens.
