Here are some similar games to The Cow Game, that you can play whilst travelling!
My Cow (with elaborate rules):
https://web.archive.org/web/20170512173216/https://blogs.agu.org/georneys/2010/11/06/the-cow-game/
Cows on my/your side (Number 19 on the list):
https://www.buzzfeed.com/fuelthejourney/cows-on-my-side
Road trip Bingo:
https://www.autoblog.com/2010/02/25/in-car-games/
My Cow/Dead Cow:
https://web.archive.org/web/20151027153457/https://roadtrippers.com/stories/10-kid-road-trip-games?lat=40.80972&lng=-96.67528&z=5
Car Spotting game (Punch Buggy /Punch Dub / Slug Bug):
https://en.wikipedia.org/wiki/Car-spotting_game
Spotto (With printable playing card):
https://www.reddit.com/r/australia/comments/1ls9tag/spotto_school_holidays_road_trip_time_to_repost/