I got some free about 3 years ago with some Redex and have only nearly finished the bottle.
You put it on your windscreen and above about 40mph, any rain that hits the windscreen just forms into globules and shoots off the top - it's brilliant.
On the motorway, it can be raining hard and you DO NOT NEED YOUR WINDSCREEN WIPERS ON

Got to save a bit of fuel though through not using electrical equipment !!!
