A few years back, I had this same dilemma with my HCH (Honda Civic Hybrid). So, I purchased some magnetic sheets. Stuck the stickers to one side, cut around the sticker, and stuck them to the car. I would seldom drive on a highway with HOV lanes but when I knew I was going to or might hit traffic, I would pull them out from the glove box. The small front one was kind of weak and sure enough one day when my speed was up there...folupe. I wasn't sure at first, but it was gone once I got out to check; three are better than none. Worked great other than that incident.
Don't know what I am going to do when I get my MS since it is all aluminum, but I will come up with something. Maybe a magnet on the inside of the panel. Or that magic picture hanging tape. Or maybe some clear vinyl a little larger than the sticker holding it in place. Yea, I like that one.