Hey guys I'm using this cleaner namely FormalHero, or something similar which is very effective towards these rain-x or water-stain. It costs about Rm11 in Giant. It says, apply it on a wet cloth and rub it on the clean windshield, but no it doesn't work this way. Just apply it on a DRY cloth and rub it on. VERY effective. ALL existing stains will be removed after a rinse. Hope this helps.

. I'm a proud owner of a Proton Inspira 2.0E. 2012 model, purchased & collected 30th July 2013 which makes my car is only 6months old. All 4 tyres are Continental which came with the car.