Littering. My gawd, I hate litterbugs, especially ones that throw stuff out their car window. You're obviously driving somewhere, and that "somewhere" probably has a trashcan. Just keep your bottle in your cupholder or put it on the floor of the car and WAIT UNTIL YOU GET THERE. It's not that damn hard. Don't give me that "my car will get dirty" bullcrap either. If you were willing to eat/drink in your car in the first place, you already risked spillage. You can handle an empty bag, can, bottle, container, or whatever sitting with you for the duration of your car ride.