Since Rolls-Royce introduced these about 20 years ago everyone seems to be getting on the bandwagon - you can even get them on a Mini !
Rather like spinners I suspect their popularity will be fairly short-lived. Rolls' tend to lead a relatively pampered existence; how well these more mundane caps will cope with the mud and crap of everyday driving I guess remains to be seen. Have to say, if I did have a C8 I don't think these would be high on my list of desirable mods...