I think that cars should come with built-in signs. Like so you could communicate with other drivers. Maybe you could have a touchpad in your center console so you could select one to display on the side or back of your car. I'm pretty sure it would be beneficial to have signs that said things like: "Dude, use your blinker", "Sorry for cutting you off!", and "Stop picking your nose".
(When you used that one you'd put on your sunglasses and look the other way so the driver thought maybe it was an accident...)
And when you were out of gas and coasting 1.6 miles to the closest gas station you could put out your sign that says "Sorry for going 3 miles an hour, my tank's dry." and then the guy behind you wouldn't be riding your tail, honking his horn, and giving you a whole flock of birds.
Plus it would make driving a lot more entertaining.
Like when the sign in front of you said "Honk if you think it's okay to drive while wearing a snuggie", or "If any of my six deer heads fall out of my trunk, please stop immediately. Deer are people too."
And of course this wouldn't be distracting at all.
And obviously, my next invention would have to be a company that sells bling for your car signs. You know, so you could put purple rhinestones and feathers on your sign that says "Dude, your truck smells horrible, and when you stare at me at stoplights, it makes me uncomfortable."
Now that you see how busy my brain has been, you can probably understand why I forgot to post this bark back around Valentine's day... If you can forgive me maybe I can give you some free car-sign bling someday or something.