Even if you don't buy a specialized rescue tool, or seatbelt cutter, and you don't EDC a knife, you could have a small partially-serrated folder clipped to the side of your seat, or in the center console that would make quick work of a seatbelt. I have one there for just that purpose, it's not my favorite, but, it'll do the job. For the faint of heart, some EMT cutters would probably do the trick too, and are handy if you need to cut a penny in half to make change at the tollbooth...