Points
Player points are based on seating spot
Last-row seats
Score pub signs, and count the legs!
A British institution: pub signs are the scoreboard. Playable on any road with pubs, so, any road.
Watch for pubs. First player to call a pub's name claims it, then counts the legs in the name: The Red Lion is 4, The Queen's Head is 2, The Coach & Horses is a coachman plus four horses, a fortune.
Add the legs to the spotter's seat as points, or agree a simpler scale like one point per four legs.
Argue in good faith: The Green Man has 2 legs, yes. Whether The Fox & Hounds means one hound or a pack is a car ruling, and the ruling stands for the whole trip.