Here's a DIY build-in car charger for iPad:
Edited by Moderator
It's not dedicated for used as iPad charger. Actually it's a universal in-car USB power source that can be used to powered many digital devices such as GPS, video recorder, cellphone, bt earphone.. But the bigger one has 2A capability to charge iPad, and there's a built-in resistor network to be recognized by the iPad as a charger.