Originally Posted by pho_shizzle

Be very very very careful when diluting IPA (Isopropyl Alcohol) with water with the intention of it being sprayed all over your car. There is a lot of misconception with the ideal dilution level of using IPA on any surface of the car. For example, many new High Solids Clear Coats are considered to be "Alcohol Friendly" meaning that such products like IPA beginning at certain strength levels will have the ability to penetrate and soften the paint clear coat, and in the worst case scenario can leave your paint with a wrinkled/crack or permanent stain. Stronger the mixture, quicker it can bite into the paint.

Everyone who uses IPA on the exterior paint surface of your car PLEASE TAKE EXTRA PRECAUTION!

The proper dilution percentage is 10% of IPA to remove surface oils and other residues. That probably will not be enough strength to beat the icing you are speaking of. Also it will dry out your wipers, leading you to spend more money else where. If that is the case, I recommend you try and find another solution to beat frost.