all red corsas seemto do this, my das corsa 06 plate is going like this, he washes it every week or so but it bleeches like a b**ch, i see a couple 56 plate corsas on the way to work and they are worse than your gfs car.
my grampas old astra done faded really bad it was supposed to be deep navy blue, but it was pretty much white on the roof, fading to sky blue towards the bottom. only time you got the natural colour was if you scuffed the paint.
i'm gonna steal the aggressive compund from work and try it on his car see if it makes a dent in it.