I have three kids, youngest is now nineteen, and my answer is simple. Don't lets the kids eat or drink in the car.
If all you do is protect stuff from the kid's accidents, carlesness, destructive behavior you're not teaching them anything. My daughter has a friend who in her late teens still gets nail varnish on the seats of her dad's car. But who allows her to put nail varnish on in the car?
No exceptions. My wife made an exception for a McDonalds years ago and my son, who was maybe about four at the time, dropped a chocolate milkshake on the back seat of the car. Never fully got the stain out.
There is no need for a child to eat in the car. If they don't do it they'll never miss it. If you let them they'll expect it. Some good reasons not to let them. Apart from the inevitable mess, if a kid in the back chokes on a sweet while you're doing seventy on the motorway they could be dead before you can get into a position to deal with it.
Same around the house. Don't shield things from the kids, teach them to be careful, to not touch certain things. You'll end up with well behaved kids who will look after their own stuff and respect the belongings of others.