Answer:
Using logical reasoning, if they collided front to front the engines would have a chance of implosion. But unless they aren't the same type of vehicle, e.g. a honda civic hitting a honda civic, there wouldn't be as much damage as the same vehicles hitting each other. Unless the counterpart is taking in big trucks aswell, such as a semi hitting a bus, then there would be a mainstreet explosionary blast most likely. But either way both will be messed up BAD.
I believe the answer to your question will be atrioventricular but don't cross out pulmonary it could possibly be the answer.
