Originally Posted by Anthony
officers only really have the right to search your vehicle at your consent, a warrant, or if they have a sense of fear while approaching your car (life is in grave danger because searches can only happen in the cabin of your car readily reachable by you). When there is no fear involved there can be no search, so act calm and keep you hands on the wheel (in open view) and just be polite. They have no reason to search your car and if they do it is then illegal.
If you do deny them a search, though, you better be damn sure there's nothing illegal or wrong with your car that they can see from the outside. The standard of probably cause for a car is much less than for a house, and evidence taken from a car does not necessarily need to have a warrant attached to it. Anything illegal on your car is then grounds for impoundment, and in impound they have all the time in the world to search your car.