i got a decent car cover from hamilton classics, taylor made for the coupe, storm proof cover that is breathable and protects against the uv effect. cost me 180 £
the cover is fleece lined, so as wind blows it polishes the car as well.link here...
http://www.hamiltonclassic.co.uk/acatalog/OutdoorCoverCarBreathableSoft.html#aMT my experience of this cover...
does it keep the rain off - yes
is it breathable... to an extent yes... these is sometimes condensation on boodle panels from water under car evaporating.
does it keep the uv off - yes, i kep windows just open about half inch when covered to let heat out.
dunno about snow yet.
hope this helps