Boolean modifier messing with color, bug?

So I have this image with a car that has two materials assigned to it. When I apply a Boolean modifier to the car it tweaks all the assigned colors on the car. Anyone see this before? Blender Version 2.68, in Cycles.

If that’s only blue messed to black, normals got haywire.
In edit mode: select all (a key once or twice, depending if there is anything selected already) and Ctrl-N.
Model instead. Be safe.

@eppo, thanks for the advice but this has no change on the outcome. It seems to be an issue with the Boolean operator, because one that is removed from the model the color sorts itself out. Unfortunately, I need that operator on the car.
Anyone else have ideas?

I’ve tried to recreate the issue in a new file with just a sphere but have not had any success.
Here is a sample file of the car and the issue working. I must be missing something somewhere.

When you add the Boolean operator to your lowpoly model (not advisable in general) it goes from 476 faces to 674. I’m guessing the resulting hideous face rearrangement is breaking your material assignments. If you separate the wheels from the body and use the Boolean modifier on just them, the problem goes away. Parent the wheels to the body so they stay with the car.

@CD38 this doesn’t solve the issue though, plus then the boolean is only on the wheels when I need it on the car so when it passes through the cube it’s disappears. It’s animated. Not just the wheels are black if you look at the model in edit mode you’ll see I also have color applied to the windows as well.