material for outdoor window covers

Dan-nickie. Gave it a try many years ago and got ride of it after the first year. Found the stuff to be next to worthless for keeping out the heat. It did work well for adding insulation in the winter but then its like living in a submarine.
I made a complete set of shades for all the glass using solar shade material with 95% blockout mounted on the exterior. World of difference but I would not recommend or try driving with them on.