I want to make my own car cover but I can't remember the name of the cloth they are made from. what's it called?

If you google "non woven fabric" you'll no doubt find what you're looking for.
HTH.
Cheers, Pewe10

PS Just to say that if you can find one which is rip-stop that would be better than straight non-woven which has a tendency to rip/tear.

[Edited on 20/11/12 by pewe]

Goo selection here http://www.profabrics.co.uk

Tyvek for waterproof and breathable.