Try an ice cube to harden it then peel it off.
Use a can of spot shot to loosen it up
I know this may sound weird, but try using scrubbing bubbles (the foam) that you would use for bathroom use. It actually took black tar out of a pair of my jeans. It will discolor or fade colors.
Take a towel or washcloth and an iron out to the car. Put the towel over the crayon and rub it with the warm iron to melt the wax and it'll cling to the towel. It's the same thing you would do for candle wax.
Seems like the crayon stains have set in on all your clothes. You can remove these stains by using WD-40 which is available at hardware stores. The whole process can be found at the following link:
You need to warm the seat up so that the crayon melts again and you then need a silly and also very hungry cat to slurp up the crayon. I have not tried this myself, but my great great aunt swears by it!