1. Not using a turn signal when turning or coming to a dead stop to make a turn when it's not necessary (usually on a right turn).
2. Tailgating (while driving, not the kind with chilling before a football game).
3. Cutting someone off or preventing someone from merging onto the freeway.
4. Like
@JoChris stated, irritating noises, especially constantly clearing your throat. But maybe some people just have more phlegm.
5. Spraying air freshener liberally or using smelly cleaning products. It's too strong.
Okay, I'm sensitive to smells and noise since I sometimes have migraines and the last one I had made me wonder if I could die from the pain :-(
And have never liked rude drivers and try not to be one myself. I loved visiting Colorado because the drivers were so polite! Contemplated moving there and probably would've if it weren't so far from my family. They let you merge in Colorado. My kind of people.