I use covers too, BUT to avoid scratches, I bought two queen size soft flannel/fleece sheets and sewed them together short end to short end, and I lay that over my car to protect it from dust, etc while it's in the garage, and it's UNDER my regular cover when the car is stored for winter. You may need to use king size depending on the size of your car, but the queen size covers my Vette to past the mirrors to just past mid door. I live in PA and have an unheated garage as well. But I've used this method for at least 20 years and it hasn't failed me. When it gets dusty, into the washer and dryer then back over the car.