There are few things more irritating than being in the car with a bad driver. A factors test:
1. The light ahead is red. Inexplicably, the driver actually speeds up to reach said light more quickly, and then must slam on the brakes once he or she approaches the it, jerking everyone in the car around (see Newton's 2nd(?) Law).
2. Tailgaters. Why do these people do this? What do you honestly hope to accomplish, other than rear-ending someone and increasing your own insurance premiums? It's not making you any tougher, you aren't teaching anybody any lessons, and OH, jack knob, here's a newsflash--you're the one who's going to be liable for the accident, even if it's because the person you are tailgating has done something stupid.
3. Cellphone--or worse--texting drivers. Some of us can have a brief conversation on our phone while still safely operating a motor vehicle. Many of us cannot. None of us can while texting.