so don't keep us holding on... what's the first best thing??!! 
http://www.golfgtiforum.co.uk/index.php?topic=54884.0 ? 
This stuff lasts 6 months plus - especially if occasionally wiped down with Autoglym AquaWax after washing 
Hi guys i have a MKV with a huuuuuuge plastic arse which is only a couple of months old. do you guys think if i applied this stuff regularly it would prevent fading.
Hi Top Cat,
Love the new sig

Perhaps you could get the graffiti photoshopped to say "TC is King!" next to your bonnet

Most products like Autoglym bumper care or tight nothern equivalents like shoe wax are intended as cures rather than preventative. But, I would suggest that any product that sits on the plastic and acts as a barrier to oil, pollution and UV light, which are the worst things for plastics, are a good idea.

There are a few very good spray - wipe products that are trim safe now. AG Aquawax is one and I have noticed that it can sit ontop of proprietary bumper care products and prolong their effectiveness. Guy or someone will probably be able to point you in the direction of a good sealant for plastics (if there is such a thing) because he has a greater knowledge of whats out there.
Edit I see its already happened!!!!!!!!!!