I have spotted a few threads on here regarding the cleaning of faded plastics on bumpers and the like and have decided post my two-penneth worth. (If nothing else, it will boost my post count!!!)

With no roof bars fitted, and after a quick wash, the top came off in under a minute and although generally not too bad, it did seem to have a lot of faint stains and marks.

Having nothing else to hand, I used Autoglym Instant tyre dressing (It came in a bag of stuff I got last Christmas)....I rubbed it in firmly with a rag, leaving for a while then buffing off with a clean cloth. Did this twice and it has come up really well removing (or disguising) most of the marking and leaving a bright if somewhat matt finish.
Not sure how long it will stay like it and I admit it was bloody hard work but well worth the effort.

This has worked for me but as I say, I have no idea what the long term results will be so copy at your own risk

Vinyl wrap and a ginger dog are all you need

Armorall, totally unbeatable.

OK, an investment in a bottle of Armorall it is then! Woke this morning to streaky back pillars, so tyre dressing is not the answer.

Autoglym bumper care for me - does a good job on the engine cover as well !!