1st try some car polish....most likely that wont work, but try it.
Get some bug and tar remover from the auto parts store. Spray it on and let it sit 10 minutes or so. If the adhesive is not easily removed or remains quite tacky reapply and try again. If your out side and its cold out the adhesive will be hard, get a hair dryer to heat up the area B4 and during removal.
After its off be sure to clean the area and re-wax it
.....what ever you use to remove the gunk will be forever covered in it, use something that is not your wife's favorite dish towel......