Coldplay... aren't they that irritating muzak band. Maybe I have them mixed up with someone...
Nope. I remember that song "Yellow". Heap of greenish, steaming **** straight from a dog's arse and onto the dinner plate of pop culture. They're not actively irritating, like, say, Godsmack (whose appearance on every rock station in the Universe officially signifies the death of the genre and the birth of something new and horrid that should have died and dissolved away in the metaphoric womb for the good of humanity), but that's hardly a redeeming quality.
Anyway. I scrapped plans a year or two back for a directionalized loudspeaker-subwoofer that'd return fire at earthquake levels and tear the mother****ers' mufflers off from twelve feet, but the setup for it cost almost as much as just ramming them and buying a new bumper each time, so I scratched it. Someday, though, when I have, you know, money, that'll be something to aspire to, though...
However. Something to consider- most drivers expect, at absolute worst, aggressive driving as comeuppance. Take every opportunity where you're in the passenger's seat to lean out that window as you pass, wave a good-sized hunting knife, and scream stringed profanities at them in every language you know and a few you made up at the top of your lungs. Throw roadkill and get the driver to try and run them off the side. I can guarantee that they will behave, permanently. And if you hide the knife under the seat, you can just say the bastards musta been on drugs if the cops show around.