Head-on collisions are among the most dangerous ways that two vehicles can crash. The impacts occur at high velocity because the speed of both cars add. Poorly executed passing on two lane highways often cause this type of accident. Although passing another car using the oncoming traffic lane will always be dangerous, bad passing habits increase the danger to unacceptable levels. Here are six dangerous passing practices: Passing a vehicle that’s traveling near the speed limit. Exceeding the speed limit is illegal regardless of the circumstances. The passing zones, which.