Police can open your car door and even ask you to step out of the car.
If a police officer pulls you over and they tell you to get out of the car, you should step out of the car as not doing so can get you arrested for obstruction.
Don't argue with the police and simply open the car door and step out and things will go much smoother.
Even if you have a warrant, not stepping out of the car will not protect you from getting arrested.
If you refuse to step out of the car when the police officer lawfully orders you out of the car and you fail to open the door and step out and your windows is up, the police will simply smash your window and pull you out of the car.
Once the police get to the point of smashing your window out and pulling you out of the car, then you will certainly go to jail and face more charges, including obstruction.
Although if the officer does not have a lawful reason for ordering you out of the car, then it can be a violation of your fourth amendment rights and any evidence found in that case, would be deemed inadmissible in court.
Although exceptions to the warrant requirement for having you removed from the car and searches of the car include consent, hot pursuit or plain view doctrine.
Police can also open your car door if contraband or evidence of a crime is visible from the outside of the vehicle.
Police can open your car door in situations like after a high speed chase or hot pursuit or if there's an immediate danger to the public or officer.
Police can open your car door if they have a legal search warrant.
Police can open your car door if you or another person with apparent authority voluntarily gives the police consent to the search.
Police can open your car door if an officer has concern for their safety like being unable to see the occupants of the car or their hands or if the location is dimly lit.
And police can open your car door if they have reasonable belief that a crime has been or is being committed or is about to be committed.
When police cannot open your car door is without justification such as for a better look or out of mere suspicion or unless they have probable cause or a warrant.