I've read several traffic related stories lately, mostly about the new tailgate detecting laser system deployed in Airzona. Interesting, but I thought of a far more interesting result.
Everyone seems to have a cartop cargo pod these days. How about we spruce one up?
First, bolt on a few fiberglass Sidewinder lookalikes. I'd probably modify them so you can point one forward and one behind. Add cones to the engine are to both disguise the fake-ness and help with the aerodynamics.
Second, put a couple of windows in the front and rear. Behind these put a surplus 10GHz or 24GHz Gunnplexer and horn (the core waveguide of most police radars) and a 905nm IR laser with optics to provide a flat cone (police laser radar). This will let you light up someone's life if they're the speedy paranoid type or the annoying tailgater. This will have no effect on those who don't have radar detectors. I'd probably have to add in an LED system in the missile "nosecones" that would pulse in time with the radar pulse. Wonder what people would notice and believe from the movies...
Now, add a custom "I support direct application of traffic law" bumper sticker and some fake (or real) vehicle battle scars, and you'll have yourself a winner.
Not a cheap project. Figure $50-100 per emitter, plus the cargo carrier plus the missiles and mounts. You'll probably end up spending $1000 on this toy in the end.
A lot of space will still be available. What to do with it?
Careful design would allow you to place an automotive PC plus a bunch of sensors up top. Hook up a lot of cameras and you could provide a 360 degree tour (plus traffic stops by curious cops!). You could also run an algorithm to track speeders and get actual speed from them (it'd take some additional circuitry on the gunnplexers). A dedicated computer controlled pan-tilt-zoom camera turret would let you get a REAL good photo of them, too. GPS would be an obvious addition, too.
Now, silly and probably (highly) illegal stuff. Drill out and place LOTS of RGB LEDs in the exterior. Almost invisible when off, you could give yourself whatever lights you'd want depending on the control program. Keep the top clear and put a plastic bubble on top with a fake (or real) radar antenna spinning in it. THAT would get some attention. Maybe you could claim it's a weather radar? I know some people would actually want the missiles on the side to shoot, but I cannot condone that, nor having a mine dropper in the back to bomb that tailgater with grenades/caltrops/deer carcasses.