Slightly off topic but has anyone used Commas 'Rain Clear - Rain Repellant'?
I brought some from Wilkos for £3.99 and it is amazing! I put it on my other halfs car, you have to polish it onto all of your outside glass and mirrors - let it haze and apply it again. Then when it's hazed again you buff all the areas until they're smear free (took about half hours elbow grease) The next time it rains the water just beads and runs off in the airflow.
I was driving it in heavy rain yesterday and I barely had to use my wipers over 40mph as the rain just ran off the screen in the wind! Get some - I promise you wont regret it, it also cured the squeeky wipers. You can use it on your lights to stop them getting as dirty. I've treated my glass coffee table (I have two massive Dogue De Bordeaux - they slobber everywhere!) my TV screen (again dogs!) bathroom mirrors and my glasses.
The best thing is i'm collecting my new Panda next Saturday and I called them up and persuaded them to treat all the glass and mirrors if I provide them with the stuff - result!