I used to use Autoglym and thourght it was the monkeys nuts untill I tried Zymol.
Zymol is the king of polishes.
I'm not talking about the cheap all in one stuff that halfords sell, that is for every day use.
This stuff can only be got on the net so far, and its pricy. It consists of 3 stages shampoo, HD cleanse and wax. All their products are 100% natural no nasty chemicals.
The shampoo will get all the rubbish off your car. HD cleanse is the real cleaner, this will take off tar and even restore hazzing, but not in an abrasive this has no chemoicals or abrasives in it and will not take any paint off, just improve it. The wax then seals it. Fantastic. (expect to pay about ?100 for a kit which includes all the aplicators, but the wax will probably last you a good decade.