the Werkstat acrylic kit is excellent for silver and white cars, it has three parts. I've spent loads on wax, sealants, etc and this kit beats everything hands down. Kit consists of:
the prime - cleans the paint and puts a base layer of protection (I apply about twice per year)
then the Acrylic - apply with a MF (I apply roughly every three weeks)
The Acrylic gloss (50/50 of water and acrylic) is the the third bottle and that can be applied in between the Acrylic layers every other week.
It gives fantastic beading in the rain and a super shine in silver and white, the more coats you give it over the months the better the shine gets. It gives the car the look that it's covered in shiney cling film if ya get the idea, the reflection off the paint is the best I've come across and I'm sure those of you with silver and white cars will agree me in saying it's bloody hard to get a good reflection of our colour paints. It gives excellent protection during the winter, very easy to apply, the dirt finds it hard to stick to the paint so a quick shot of the power hose blows most of the dirst off before you even start cleaning.
You should give it a go, you won't regret it.