Has anyone ever made a "junker" car cake? My son's 16th is coming up and I want to make him a rusty, beat up car So far I'm only thinking gray (primer) icing, with some rusty spots, but I'd love some more ideas...

You could use a terracotta fondant under that Duff's silver spray (at Michael's) and rub it out in spots to look rusted. You could also PM someone who's done a "Mater" (the rusty tow truck from Cars movie) and see how they did it.

I did a Mater cake a few years back (it's not in my pics, it was for a nephew and was a total nightmare to cover) and I just did it in chocolate MMF and then hand brushed some of the blue, green and such on it. It was for a big party so I set it on top of a sheet cake and then piped lots of grass up under it and around it so that it looked like it had been sitting there for a while. It turned out okay and everybody loved it.