Me too, me too! hahaha.....
But I recently stuck a DIY port-a-potty in my car & it's awesome! I used it for the first time the other day- it's a plastic tub, about
8x8" with a snap on top, lined with a plastic bag. Nice! But yeah, accidents suck big time. always carry a car kit in your car- plastic bags, TP, baby wipes, extra underwear, maybe extra pants, etc. Unfortunately you're not alone- I think there are far more members in this club than you'd like to believe!