well to my way of thinking, bumper stickers are made from strong, water resistant paper (or perhaps some sort of plastic coated paper) with adhesive on the back (and i am impressed that Consuela had one ripped off her car, my experience is the bumper sticker is stronger than metal, and its easier to rip off the whole bumper than to remove the sticker!)
the stuff in the windows--most often (but not limited to) college or university names, are decals. --these too are pretty permenent.
side window often have decals that are required for use of local parks, parking lots, or are attempting to convince a policeman that the driver/owner of the car is also a police man(or the father/mother/sister/brother of one), and shouldn't be given a ticket.
a smaller percentage of side window decals advertize alarm systems, or other other stuff.
nowdays, some of the things stuck on cars are magnets.
you can buy magnetic sheets no thicker than card stock and run them through a printer.. (though most home printers don't have water proof inks). the commercial ones are made with water proof inks --but they are often not sun proof, and the colors and text rapidly fade.
they are also often dye cut, in the shape of a loop of twisted ribbon, so its not clear if the ribbon was Yellow, or red, white and blue, or pink or some other color-and which particular cause you are/were supporting.
the Magnetic ones are popular because they are easy to remove.
large magnetic signs are also available.. and these are used by hobbiest part time independant entrepenours as advertizements --they can place them on the family car when they are the Avon Lady and hosting a party.. and peel them off when they are just mom and grocery shopping. )
as for all the other stuff, (country code stickers, AAA stickers, well i don't quite think of them as bumperstickers..
bumper stickers, even (especially?) political ones are not very popular in NYC--
for years, i think the most common bumper sticker in the north east was "This Car Climbed Mount Washington" but some people objected to having it stuck on their car, and now its just placed (with its backing intact) on the windsheild, and fewer and fewer cars sport them.
