Just wanted to share an experience of a product which I think is the nuts. After a normal wash down of the car, I let it air dry then used a product called "Showroom Shine" by Greased Lightening.
The product comes in a large spray bottle and 2 microfibre cloths, you spray the product sparingly all over the car, glass and all, then rub all over with one cloth, then follow yourself around the car with the second cloth and buff it off. I'm sure there are a tonne of these sprays out there, but seriously impressed with this.
Also they give you the sell that it leaves a protective barrier and all that junk, well, its no bull, a 130mile round motorway trip, followed by a nightfall of rain, car still gleaming! Used 4 times now (1litre supposed to do 10 'washes') and easy, quick and great to use.
At about 15 squids, I think its a pretty good product - just wanted to share
(Before the "This Post is worthless without pics" gif appears, I will post once I do my next wash - next weekend )