Are the ash-trays full? If so, maybe you could change your car for a new one. Go for black leather this time, it doesn't show the dirt so much. Seriously though, it is possible to clean but do it gently, get a leather cleaner and follow the instructions. It might be a good idea to fit some car seat covers to prevent it happening again.
A little alcohol should get it off, but try it on a piece of hidden leather 1st just to make sure it doesn't affect the colour. Methylated spirits if you have any or surgical spirit or Isopropyl Alcohol (available from suppliers of electrical components like RS and possibly Maplins). Isopropyl is beat as it doesn't contain any water and the others do.
I can assure you that the hairspray one works Jayne. Don't use too much, and then get a damp cloth and rub the mark off gently.
Hey - lose some weight off your bum!! : )
x
Whilst I have had a blue ball point ink on a white leather jacket for many years, i have never attempted to do anything about it; however on your behalf and on my own i will take steps to remedy this with through consultation with the nearly infallible girls at the local craft shop! There is nothing these women cannot fix! (save bleach stains which are, unfortunately untreatable :( ) I will hopefully get back to you tomorrow morning as it is a bit late tonight to go bothering them and have only just read your post!!!