want to put images on the warthog like a double kill medal or a extermination
That might be pretty cool.
I could only imagine that customized warthogs and other vehicles would be used only in race.
-Yoink!- my Hog.
Yeahhh baby 
yea what papercraft said, i dont like the idea of medals though, maybe flames and stuff
Halo 4 should have something like that, like the custom hogs in CE.
Imagine if you could customize the Warthog the same way you can customize your Spartan. =D
I want to draw a picture of a catfish on the side of my Warthog…
I’m sure if there are color and decal customizable options for vehicles they would be very limited. I could see something similar to your armor emblem options, but nothing as extensive as putting medals or kill counts on it.