Reply #1: It's a good idea if all you ever do is drive in the left lane.

[Pithlet]

But it's going to look pretty stupid when you're driving in the right hand lane down a side street, assuming this is even for real. Besides, the left lane is for passing, and as long as the driver is actually passing someone, I don't get all that upset about it if they aren't going as fast as I think they should. These stickers will mostly identify the people who think left lane = Autobahn. I hate pokey people who stay in the left lane, but I hate the aggressive assholes who get up on my rear end when I'm passing someone because I'm not doing 100 mph even more, and then flash their lights at me because I didn't get right back into the right lane and cut off the person I was passing. Slow drivers are annoying, but I think this left lane mentality creates more of those aggressive assholes who think they're entitled to go as fast as they want to in the left lane no matter the traffic conditions. In fact, just today, I was nearly hit by a jerk who got pissy and aggressive with a slow left lane driver and cut me off trying to pass him on the right. He was so busy making gestures at the slow left lane driver that he wasn't paying attention.