How much should on pay towards my teens car?

My daughter bought a 2005 Jetta for $8500. It's a nice car, we bought it privately. She put down $1300, I'm paying the tax, title registration and inspection (about 800). I'm paying the car insurance and 1/2 the $135 payment ($140/month), my daughter will be paying $75. She will be attending a local college, she also works about 20/hrs a week. I hope I am being fair? Thank you.