Andrew I can only tell you about my car cover i purchased back in 2014 .The cover was purchased for my W124 .Reason is i can not use the garage .
Well the cover owes me nothing it was used every year from 2014 thats 8 years .This year i fitted the cover on the 1st November .But after the last weeks bad waeather i checked on the car to find it was very wet on the boot area . so i have just ordrered a new one exactly the same .From the same company on Ebay PJ Covers I had the fully waterproof Monsoon cover because it is only used in the winter, November till March . The cover as vents on the sides and wing mirror pockets .With out these i would not buy any other type of car cover . With out the mirror pockets the cover rides up over the mirror and the cover looks like a tit on a hay rick . But i do use a number of cotton sheets under it just in case.