Hairspray. Cheap kind... aquanet... spray until wet, wipe off with paper towel. Repeat until it's gone.
Thanks, Rae Vynn, but it doesn't seem to be working. Do you have to let the hairspray sit on it a while? If so, how long?
See if your local Home Depot or Ace Hardware has a product called Moetsenbackers. It comes in about 6 different kinds, one is for pen, ink and marker. If that one doesn't work, try the graffiti one. I keep one of each kind on the garage for laundry day. BTW you probably won't get all of it out. It will have soaked in to the leather and "dyed" it. But you might get it to fade out and be less noticeable. I have the cloth. I got road tar on my back seat. It came completely out.
I just cleaned ballpoint pen writing from my Expedition leather using Huggies baby wipes. Hope this helps.
Thanks for the tips, we will try them! The pen marks are in my Chrysler 300C which would be sold in order to buy a Prius. My husband is quite reluctant to sell that car even though I am the one driving it! However, he seems motivated to get these marks out which are the only flaw in my otherwise perfect car. Maybe he is coming around to the idea of getting a Prius!
Since you are getting rid of the car, you could also try Isopropyl alcohol, but the high alcohol version, not the common version of 70%, the 91% or better 99% if you can find it.
Oh, if it's old ink marks, the hairspray won't work. Sorry. I thought it was a new mark on your [new] Prius. Yeah, time to drag out the big guns...
OK, the baby wipes didn't work. Probably will try the alcohol next as I'm sure it's cheaper than the Moetsenbackers cleaner. Yes, Rae Vynn, I wish it was new marks on a new Prius! Not now, but maybe soon! Thanks all!