You can probably relate to the experience above. If it's not someone tailgating you, it's someone cutting you off, or not properly yielding to you, or perhaps not letting you merge. There are lots of opportunities to feel wronged and aggrieved on the road.
For me, these situations would induce a rush of negative feelings and sometimes even lead to dangerous retaliatory actions. Eventually I knew I had to re-evaluate my approach to driving. I had to reject the negative feelings and their justifications. Further, I realized that some of the same feelings and rationalizations that fed my responses were the same ones that lead people to justify the evil of government. In particular, there were three psychological obstacles I had to overcome before I could "let go" of road justice and instead adopt road pacifism:
1. Desire for revenge
This was the most base response of mine; the desire to pay back evil with more evil. If another driver caused me anxiety or stress, I wanted to inflict that same suffering back onto him. But the primary effect of this desire was to cause more suffering for myself! If I did not act upon my desire and instead let the other driver "get away" with it, then I would stew in loathing and frustration. But acting upon my desire would only serve to escalate the situation and perhaps even endanger myself and others.
I realized my responses were unhealthy and harmful after one incident where I tailgated a car that had just been tailgating me. I was glad to be causing the driver anxiety and stress, just as he had caused me the same a few minutes before. Now he was in the same situation I had been in, only the situation was escalated with more tension. His response was to hit his brakes, and I almost bumped into him. After counting my blessings that no accident had occurred, I understood that my desires for revenge on the road only caused suffering.
2. Justification of punishment
The desire for revenge was an emotional response to situations on the roads where I felt wronged, and it was the strongest influence that I had to overcome on my way to a more peaceful driving practice. But there is also a more intellectual counterpart to the base desire for revenge, and that is the justification of punishment. That is, once I could suppress the emotional response that I knew was unhealthy, I was still left with the thought that enforcement of rules and punishment were necessary. After all, there have to be some rules to dictate how to behave on the road, and we all had to follow them.
But this line of thinking can only lead to support of institutionalized violence. Once you start drawing arbitrary lines to justify force, you immediately justify an imaginary government that enforces your lines. And so even if I had no desire to personally "get back" at a driver, I nevertheless would approve of (and hope for) a policeman punishing him accordingly. If there was no policeman around, I took some solace in the fact that eventually he would be pulled over for a similar infraction and be punished.
It did not take me long to realize the great contradiction in my position, which was that the people who were the worst drivers on the road, who caused me more anxiety and stress than anyone else, were the police themselves!
Aside from the issue that no one can police the police, there are lots of problems with the intellectual justification of punishment. I will highlight one here that is especially relevant to driving. This is that this justification anesthetizes one to the pain caused to others. Whereas the desire for revenge makes one wish to cause pain to someone else, the justification of punishment makes one unsympathetic to pain caused to others. It was, after all, "what they deserved." Ultimately, this coldness and lack of compassion struck me as potentially more dangerous than the desire for revenge.
3. Thinking in terms of external rewards or punishment
Even after intellectually accepting that the desire for revenge only caused suffering, and that I could not justify punishment, there was one niggling issue that prevented me from accepting road pacifism. This was the more existential moral quandary of why we should do good for others instead of evil. Or more relevantly with respect to driving: why not drive like a jerk if it gets you what you want? Shouldn't there be some ill consequences for driving like a jerk?
But these questions rely on a sort of materialist way of thinking, where we think of good and evil as external things that happen to us. If we see someone drive like a jerk and get away with it, we think that something good happened to him because he met his goals without any ill effects to him. It's similar to that old childish question: why do bad things happen to good people?
I believe that the solution to these questions is to recognize that ultimately doing good can only be its own reward; doing evil its own punishment. Even if an evil-doer seems to live a plentiful life and reach his apparent goals, he has chosen the wrong goals and at the very least missed an opportunity to live a more fulfilling and happy life. Happiness can be obtained by anyone and has to do not with external wealth or conditions but with how one chooses to live.