Our car also does not have an antenna, it has one of those fin ones.
We use the antenna toppers on our cordless phones and boombox antenas.Sometimes for the phone you have to make the hole a little bit bigger.
We take our leftover chop sticks from chinese food and put the antenna toppers on them and then place them in our house plants or a small glass or vase. Watch out tho, my kitties have chewed off most of the Mickey ears...