Here’s a few things that might happen that is unlikely, but then again, quite possible, during a crash or accident.

• You know those airbags that you think will save you in a last resort situation? Well, here’s a whole new way of looking at them. Think about this, in fact, it’s quite common, what if your airbag won’t open in your moment of need? But actually, that’s the least of your worries, what if your engine caught on fire? As you might already know, to a fire, oxygen is it’s food, so when your airbags do open,  it might be singed and pop, all that air from the airbags will spice up the fire to a whole new level, therefore, putting you in graver and lethal danger. 
• Okay, now for those commonly used seat belts, the tighter the better? Sure, if you want to get strangled to death. If you ever rode in a car, you’ll know that when you step on the breaks when you’re going around 80/kph, the seat belts suddenly tighten so that your body can’t move.In an accident, or just a sudden push on the break in a car going 150/kph, the seat belts are obviously going to tighten, but what if the belt was right in front of your throat before the incident?…Lets say…because you were adjusting the length of the seat belt. This will probably mean the death of you, via being strangled.
• Another situation with the seat belt could be that…In an accident, your car catches on fire, and the plastic “lock”(you insert the metal end of the belt in) melts onto the metal. In that case, you will be stuck in the car while being toasted (Yum? No, unless you enjoy eating your toasted body as a ghost…). 
• Okay, i agree this might be the least possible thing, but…whatever, just think about it…so…you’re driving down the freeway and crash, you manage to live…for now, but then suddenly the airbag whams into your face, and it’s too big, and you cant move, and the airbag suffocates you.

Those were some of the possible things that could happen because of a car’s “safety” and change from what would’ve been a few broken bones to death. Now, I’m not saying that you shouldn’t use these stuff, in fact, most of these usually saves your life, but you never know…So why am i telling you this? I don’t know…just to let you know? (Seriously…i just wanted to scare you…but still…these could really happen…and maybe to YOU.)