Seat covers! Get Zebra striped ones, they look cool and will add at least 20 more "horses"! LOL. Levity aside, I'm afraid you might need to replace or re-dye, especially if it's enamels.
My son (who is now 14 and due for
his Evilbay debut), wanted to help one time with washing the car when he was about the same age as your girl. I thought it would be safe to leave him on the inside with a dust rag. Worked pretty good, right up until he snapped off the turn signal stalk! That was a $130 part and 2 hours labor to replace. Sigh.
Ain't kids FUN?