Please be advised that OE and aftermarket car covers typically stretch from good, better, best in terms of fabric performance. Mopar's car cover product line offers the "better" category in Evolution (The 4 layer material) for the general DaimlerChrysler lineup and the "best" category in Weathershield for premier vehicles such as the Viper and upcoming Crossfire. Similarly other OE customers use Weathershield to distinguish their "best" performing car covers.
Performance categories for Weathershield rank the cover as a consistently top performing fabric in performance categories such as indoor use, outdoor use, all-weather protection, rain, snow, dirt/dust, soft touch, storage space required, mildew protection, rot resistance, and is home washable and can be dried at home as well. The Evolution Fabric is also a very strong fabric but is rated in the better category for items such as those listed above and requires commercial cleaning and air drying.
Performance Ratings for Weathershield vs. (Evolution):
All Weather Protection: Best (Better)
Indoor Use: Best (Better)
Outdoor Use: Best (Better)
Rain Resistance: Best (Better)
Snow Resistance: Best (Better)
Acid Rain Resistance: Yes (Yes)
Dirt/Dust Resistance: Best (Better)
UV Damage: Better (Good)
Bird Dropping Resistance: Best (Best)
Tree Sap Resistance: Best (Best)
Breathability: Good (Good)
Soft Touch: Best (Better)
Storage Space Required: Small (Large)
Mildew/ Rot Resistant: Yes (Yes)
Cleaning - Wash: HOME (Commercial)
Cleaning - Dry: HOME (Air)
How do I know this? I am the Marketing Manager for Viper Accessories at Mopar and we chose this product because of it's "protection from the elements" ability.