I ordered 3 yards of charcoal grey tweed from - it arrived today! I was pretty excited to try out a little bit of it... So the wife helped me cover the plastic trim piece that fits below the rear window.
I think we did alright considering neither of us have done anything like this before...
Looks like 3 yards will be enough to do both door panels, the headliner, the piece behind the seats, and a couple smaller trim pieces.