Just picked up a $15 "extra large" car cover at the local Aldi grocery store and it fits my 2006 SV8 quite well. It is not heavy, doesn't have a fleece lining, and and may not be completely waterproof (according to posts on another forum) but it does have a strap to go under the middle of the car to hold it down and it does fit. I will use it as a dust cover in the garage or car port. For $15 not a bad deal. I think they only run this deal once a year.

 

I would probably check under occasionally to make sure ther is no odd condensation. Had a fairly good one on my 1984 RX7 GSL-SE back in the day and had some weird mold looking stuff on the paint sporadically, stored in a cool garage. Came off with a good polishing but don't what something like that would do to a clear coat.