I wouldn't recommend "barricading" yourself in a car (what ever that means), but don't just follow police "orders".  In doing so you will generally forfeit your 4th and 5th amendment rights.  When police interact with the public the intentionally confuse "requests" with lawful "orders".  For one example: "Can you please step out of the car, sir".  Is that an order or a request.  Only under very specific circumstances can police conduct the search of requiring you to exit a vehicle.  If you just hop out upon request, with out knowing the exact and legal reasons for the request to be a lawful order, you have just consented to a search.