I've been using covers on my cars starting with my then new '79 C3, they will save you lots of work can be put on in under 60 seconds, trust me, I put it on everyday at my current work for over 27 years, coming off takes even less. My last Cadillac I just traded in had paint and interior that was flawless from fading and other weather related damage. However in the 7 years I owned it, I went through 3 covers (covers took the weather abuse not the paint), one was replaced under warranty (normally 3 years). I prefer a cover made using the "Noah Fabric". I live in South Florida and they works extremely well in sunlight and rain showers. If it rains and you don't need to remove the cover for an hour after the rain stops, when removed the car will be dry and no dried rain spots will be present, yes it will look perfect! The hardest part of using a cover is no one can admire your baby when its parked at work, but when you do come out and pull up the four corners, fold each half to the middle and then roll it up, you will then realize that 60 seconds of install time and 30 seconds of removal time just saved you a lot of clean-up time and your baby looks perfect as you drive her home. I don't know who's making the covers for GM, but I've only bought from two sources, California Car Covers and Big Sky Covers out of Montana. I just bought one from Big Sky for my new Cadillac SRX and the fit is perfect and it even has a little pocket for my On-Star antenae, California uses a grommet for the antenae, I prefer the little pocket.
California Car Cover for C7 $232.99
California Car Cover Company - Car Cover Materials
Big Sky for C7 NOAH $232.99
Covercraft Custom Car Covers ? Product | Big Sky Car Covers
NOAH® - A great value for outdoor protection.
NOAH barrier fabric actually stops water, yet it “breathes” to allow any trapped moisture, seam seepage or condensation to easily evaporate. The unique construction process (patent pending) results in a cover with maximum all-weather protection…highly water resistant, dust resistant, UV resistant and breathable to make sure moisture and/or heat don’t stay under the cover. Made in the U.S. by Kimberly-Clark, the fabric weighs only 4.75 oz./sq. yd., so it’s easy to handle and fold.