Most areas have similar laws in that a gun must be unloaded in your trunk OR unloaded and cased. Most areas allow you to transport guns in vehicles if you are going to or from a range, place of repair, place of purchase, etc. Many areas get bad reps because of ignorance of the exceptions to the law. DC for instance, does not allow the ownership or possession of handguns. However, you may own long guns and transport them in vehicles according to exceptions similar to the ones I described. Use common sense (a fleeting quality todayat times) and you should not have a problem. Most cops however, don't have a good grasp on their own area firearms laws, much less their exceptions. It would not be unheard of to have some gung-ho younger cop give you a hard time, but as long as you operate within the law you will come out on top.
As already stated, much depends on the area of the country you are in. Also, as long as you don't give a cop a reason to stop you, you eliminate the possibility of a confrontation.