I've had mine parked outside covered by a material called Weathershield
HP, which was made by CoverCraft. Good fit overall, with a cable that runs
under the middle of the vehicle and attaches to the cover's grommets to
securely keep it on during heavy winds. It also came with a grommet to
accommodate the antenna if it does not fully retract, which I didn't need.

After three years of Minnesota weather (snow, rain, wind, intense sun in
the summer), it still looks good. The elastic has lots its elastic-ness,
but otherwise it's holding up fine. I would recommend it if the concern is
more for rain and snow protection rather than protection from the sun.

Not inexpensive initially, but it looks as if it have a low total cost of
ownership.

Here's CoverCraft's guide to fabrics:

http://www.covercraft.com/fabric%20guide%20OUTDOOR%20rev%2012-07.pdf

Here's a link to the retailers that sell the CoverCraft products:

http://www.covercraft.com/buy_online.htm

- Kevin