Watch This Space, page-2865

I can't see this working effectively at all. For starters you'd need a bank prepared to give you a card with a fair bit of credit on it and secondly be prepared to tie your funds up for an extended period of time (5+yrs) depending on what you buy.
I'm guessing a small brand new car would be north of $20k to buy, then moving into the medium and larger family cars or 4WD's and you're starting to talk some serious $$$$'s. Somehow I honestly couldn't see any bank agreeing to this.