Your car. Just think about the forces and mechanisms invovled for this to happen. Every single day we travel at 100km/h in our 2ton at least metal box surrounded by hundreds of other people in their equally large and heavy and fast machines in a space barely wide enough to react in case of an emergency(not even considering if most are actually ready to act in such a case. All of this with realistically little training. Not to mention most people don't really pay attention while driving and certainly don't consider the life of others while doing so. It's so impersonal and dangerous. If it was a never heard of concept, individual cars driven by any normal person would be considered laughably stupid at the very best.