Hi All,
Firstly, I know nothing about fitting a cover to a V70. But I have to use covers on the cars to keep off salt air, sometimes for long periods out doors. I cover the cars in the garage to keep abrasive dust and salt air off the paintwork. But the salt air still gets inside the cars and huffs up the inside glass even though the cars are locked tight.
I have found that a cover (about $80 or so) does the job with silver plastic on the outside with flock inner lining is the most effective for use in the garage. These covers have lasted for years in the garage but only last one summer if used constantly outside, if you are lucky. More expensive covers may last only a few months longer outside before they rip and crumble.
However, most covers will abrade the paint as dust and grit become embedded in the lining. They are not easy to wash! To reduce the sandpaper effect I cover the out door car with a fluffy bed sheet under the main cover. The bed sheet gets washed every now and again. Remember to dust the paintwork before covering the car.
The photo shows my 240 with a good cover which has withstood heavy hail storms, rain and long hot sunny periods while I am waiting for the builder to build a new garage.