I have two 14 week old boxer pups (bitches). If they are in the boot of my car they poo. If they are on laps (if the kids/husband are in the car) then they don't poo. Although they have been sick instead!
If I need to take them somewhere on my own I need them safe in the boot, but whatever I put on the floor - newspaper, towel, blanket - they poo on it then walk about in it and make a real mess.
Even if they've 'been' before we put them in the car, they still seem to find some to do.
Any ideas?