There was one thing that came up during my vacation that I wanted to pass along. We journeyed to another state (California). Somehow, the driving down there seemed so much more stressful than in our home state of Washington. It finally dawned on me that the drivers around me were viewing it as some sort of competition. I can't tell you how many times I would leave a small gap ahead of me on the freeway, only to have the driver behind me pull around and jump into it.
Expressways were another eye-opener. The lights were thoughtfully timed to allow traffic traveling at the speed limit to hit all of them on the green. But everyone was so consumed with getting to the light first that there was inevitably a backup of 5-10 cars at every light, waiting for it to change. Which it did, usually just as I rolled up having driven at the posted speed limit from the previous light.
I guess I'm used to viewing traffic as a cooperative venture. We're all trying to get somewhere and if we cooperate, we might get there a little faster. These guys were all out to grab whatever fleeting advantage they could, even if it meant that all of us (including them) ended up spending even more time on the road.