I use AutoGlym Vinyl and Rubber Care - http://www.elitecarcare.co.uk/autoglym-vinyl-and-rubber-care-15-off.php?cPath=55&osCsid=a562132548c87002e6169e72dad4fd8b seems to do a good job and works on plastics too without giving too much of a shiny look, other bonus is its quite cheap.