"Caution: I drive like you do!"
"I brake for scholars, priests, and no apparent reason."
"You've obviously mistaken me for someone who cares."
"My other car bumper sticker is funny."
"I'm in no hurry; I'm on my way to work."
"I'm not a complete idiot, some parts are missing."
"I just got a new car for my wife today. Best trade I ever made."
"Back off! I'm not that kind of car."
"I may be slow but I'm ahead of you!"
"I'm not deaf... I'm just ignoring you."