I have never been one to put bumper stickers on my vehicle either; I didn’t want to mess up the car. But I did have a collection of random bumper stickers up in my room when I was younger, to say what I thought or wanted to say. I do believe that this is how we can all relate and connect in some sort of weird way. I know I look around and read people bumper stickers when I am out and about. I bet it is a real big thrill to have someone read your bumper sticker and see them  laugh, cry, or grimace at what they had just read. It defines us in our everyday lives; you know you see thousands of faces everyday, do you remember them? No. If you see a bumper sticker that you like I bet you will remember what it said and what kind of car it was.

I think that you are right when you say people want to connect.  I however, don't like it when they are really negative things or very patriotic.  One persons truck at my childrens school is all about pro-life, down on the democrats etc.  I think some people go to far and it annoys me.  I don't know why, but it just does.  It alienates me about him before even meeting him.

Bumper stickers are probably like personalized license plates, people just want to get their voice out there. I had a college friend whose license plate read "whos2sa", she definitely had a message to spread. I too don't want everyone to know what I believe, I save that for a few personal friends. I wouldn't want others to form opinions of me before they meet me. I too form opinions of others based on their bumper stickers and it's probably not fair to them, But hey, they're the ones that put the bumper sticker there for me to read, right?

I guess people that put bumper stickers on their cars don't probably care about what preconceptions people get from them.  You are probably right in that it is a way of expressing yourself.  It seems that they are always so strong in their positions.  I like the funny ones though.  They do give me a chuckle.