On long trips we kids played "Cow Poker", counting the cows we saw on "our side" as opposed to the other kids counting them on the other side. Winning the cow count was enough...no prizes at the end of the trip.........cheapo and non-"feeling" parents in the front seat. LOL
You just reminded me of a similar long-forgotten game. We called it "bury the cows" and played it the same as you except for when you drove by a cemetery the kids on that side of the car "lost all their cows" and had to start counting all over. LOL! Thanks for the memories!