If people driving about finish their bottle of water etc, they should not be throwing it outside their vehicles. It's not going to hurt your vehicle if you hold onto your empties until you get to your final destination or stopping en route somewhere - such as petrol station. Besides, some people drive vehicles that resemble tips.
On the news the other day, a lorry driver said he has to keep the cab clean for the next driver. Why can't his employer issue a bin bag for each driver for each shift and rubbish from food etc goes in there and put into the bins at the depot at the end of the shift?
If you throw out food and drink packaging whilst driving, why do you do this? If everyone stopped throwing out these, the roads would be almost free of this rubbish.
What I find concerning is the high amounts of alcoholic drink litter I see when driving.