I had two tens running free air in my trunk for awhile. One of the magnets was literally touching my car pc case, and no problems what so-ever. While most people will recommend against it (including myself) I personally had no problems with it.
Now what I wouldn't do is put the car pc in the same box as the subs, the vibrations will have more of a negative effect
and btw had you searched you would have found just this information many times over.