I have used EnduroShield for glass on my A2, and it has been on since October.
It comes from Australia, but you can buy it via ebay. It lasts one year, and even yesterday in heavy rain and mist, I did NOT need to use the wiperblade on the motorway. It works best at speeds of about 45mph+ and also keeps the side windows clear.
I also got some polish 'PTFE Car Polish - The Best Car Wax Isn't Car Wax!' again from e-bay, and it contains Teflon technology, and even after the dirty motorway trip, the car is still looking very clean, with only a small ammount of dirt on the boot, and a few dirt trails from the A pillars and the grille surround.