There is no formula for determining fault in such car accidents; it could be that one car is 100% liable or three cars are equally at fault for causing it. When we think of car accidents, we think of two vehicles on the road and both involved in an accident. Perhaps one disobeys a traffic regulation by speeding or running a traffic light. However, there could be a situation where there are multiple cars in the crash. In this case, it might be trickier to determine fault, depending on the facts.