I used simoniz back to black (get it in halfrauds)
Works brilliantly tho you do have to apply it once a month or so to keep it looking new, hers was a 97 and people thought it was new, so must have done the trick!
personally i wouldnt touch or event attemppt to put simoniz armorall or even a household product near my car- if u want to get them black again and keep them permeanent u will have to paint them with a satin black paint - the cheaper method is to use a GOOD QUALITY polish to restore the colour in the plastic- but be warned its only temporary- the rain and the sun will get its back to its former greyness within weeks.
if u get urself a good quality polish then keep applying this - u will probably have to do this every week for it to look good but over time you will have to appply it less often and it will stay black and look much better.
i could go on forever- i recommend use MEGUIARS TRIM DETAIL (£7halfrauds)?? or AUTOGLYM BUMPER CARE (£4 halfrauds)??
if u want pics of a detail on my car using meguiars products just ask u will be astonished!!!