You'll increase the cost of windshields astronomically, and they are easily broken things. Also, lots of people drive with polarized sunglasses, so the dot patterns would probably be considered annoying.They can use dipolar spaced wires in windscreens as effective antennas. Virtually loaded and gain guided. They can probably do that with thin film tech (transparent reflective coatings < 15 atoms thick) now in that frequency range.
They will be hidden by the naked eye but donning polarized shades would show them just as it reveals dot pattens on tempered glass. (from the cooling jets from the tempering process).