One heavy cover
This 4 layer cover with this type of material is very bulky - unlike the smooth material used for the HP and HD covers which stow much easier. I haven't noticed the cover keeping the car cooler than the HD, but the cover is definitely thick, and hopefully the seam stitches will last longer than the 3 years I got on the HD. It fits well and stays on in 35 MPH gusty winds without needing extra tie downs.
78 Bonneville Car Cover
I have owned the 78 Bonneville since 1985, and have ordered this Evolution cover about every 3 to 5 years as I live in the Phoenix Az. area, the Arizona summer Sun is very very hard on anything that sets in the Sun. I find this cover works well in the Phoenix area, but over the Years the cover fits looser than in past Years, and THERE IS NO FRONT MARKER on the cover which makes it difficult in install quickly. In the past they had FRONT marked on the cover.