[drunken monkey]

never tried the mesh method myself and you would need really fine mesh and good paint+airbrush for the percision needed. On the other hand, on a larger scale, I've seen pretty good effects used on architectural models by spraying through various materials.

Best way though for cars, is to stick with the foil method.
As mentioned before, several manufacturers have a heat shield patterned product. It's the simplest, quickest and the easiest method.