My '09 is garaged at night and during the day has a Covercraft Weathershield custom fit cover. My concern was sun and dust protection and I have been very pleased and people still comment how good my car looks. They are not cheap but have a good multi-year warranty. Keep you car well waxed, use a California duster if it does have a little dust on it before you put the cover on and don't use the cover when the car is dirty. I have had 3 Covercraft covers over the years and will buy from them again. Their site compares the features of the different materials they offer, they all have different characteristics depending on what you want out of the cover.
WeatherShield HP Car Covers - The Number One High Performance Car Cover Fabric for Enthusiasts