>>3287713I worked as a mechanic. Seatbelts nowadays have some "pre-charge" mechanism or whatever it's called in english that when on impact they push back very strongly and strap you to the seat. If your car falls into water it's a death sentence because there's no way you are leaving the seat without cutting the belt.
Don't know what other bad things can they do to you because I have not been in a car crash but I can tell you if you don't place the belt correctly it can kill you. In fact obese people are almost assured death id they have a front impact at any decent speed. Look it up.