Ok, here's a quick attempt (not great I might add)...
Here's the original:
http://www.dmacc.edu/programs/criminaljustice/club/dodge-viper-police-car.jpg
This is what I did:
1) I created two duplicate layers of the car, so I've got my original layer and two dupes.
2) Changed the Hue/Saturation/Lightness (select colorize) of the first Dupe layer to give it a bright blue hue
3) Changed H/S/L of the second Dupe layer to give it a Red hue
4) Changed the H/S/L of the original layer to make it dark and give it a bit of a blue tint.
5) Put the original (now dark) layer on top of the dupe layers
6) Add a layer mask to the original layer and use a large feathered brush (set to black) to "erase" where the light would hit (on the ground, on the car, etc.). If the blue layer is on top of the red layer, then this will give you all blue lights.
7) Add a layer mask to your top dupe layer and "erase" to reveal the red layer
Add a new layer on top of all your layers and add a few more highlights of the blue/red to give it more definition.
Still doesn't quite look like "real" lights, but not too bad for a 15 min job. Definitely would tweak it more to give it a realistic light look. Hey, I'm trying to be helpful! Unlike
Others around here....