N.D.
I asked this same question and have been looking for things ever since... I came to a conclusion. You'll go through too many toys and too much money b/c at one point they'll start to want new things all the time in the car and start to toss them on the floor. I do think the different drawing toys work and other toys that don't "color" the car too, but just buckle down and let her watch an educational video. We tell her she can't watch if the next trip is her nap time or if she's eating, so we have breaks with the dvd, but it's really getting ridiculous trying to find a dvd alternative that she'll want to use over and over. Just do it and pick good dvds... I do sometimes just let her get used to entertaining herself for short periods of time, but besides that? DVD......It's okay...
Hope it helps! :)