The Official site of The Yellow Car Game

The Official Rules

The Basics  
1 If a player sees a yellow car they may hit whoever they choose. The force of the hit should only be sufficient to ensure that the intended person knows that they have been hit, unless otherwise accepted by all players concerned.
1.a. The game is ALWAYS on, unless otherwise agreed by ALL players.
Cars and Colours  
2 Only cars or models and depictions thereof can be used in the game. The definition of "Cars" is a vehicle primarily designed to carry passengers. This does not include cars which have been adapted i.e. cars which have had the back windows blocked up with the intention of using the vehicle as a small van. This does, however, allow cars which have been temporarily converted i.e. a car which has had its seats folded down to transport goods or waste on a temporary basis.
2.a. Only cars which are yellow are allowed. The definition of yellow can be down to interpretation, but here are some guidelines. Gold, bronze and shades or green are not yellow. Metallic yellow is acceptable but pearlescent is not unless the colours in it are only shades of yellow. Some manufacturers call a colour yellow, just because you name something yellow that doesn't make it so.
2.b. Only cars which are at least 50% yellow are acceptable.
3 Calling out "Yellow Car" is not necessary. A player may however need to justify hitting someone by informing them of it after they have hit another player. It is worth noting also that calling "Yellow Car" could give fore warning of an impending hit which is not advantageous.
3.a. A yellow car must be called when it is view, other players must have the oportunity to see the car they have been hit for. Occassionally this may mean having to turn back, but it is advisable to play with a degree of trust.
3.b. A yellow car can not be called before it is seen i.e. you can not call for a yellow car you know to be parked around the corner before you can see it.
Resetting the game  

Once a car has been used it can not be used again in the same game, the same way that a card cannot be reused once a player has folded in a game of texas holdem.

4.a. When playing on a journey the game is reset when that journey ends. Otherwise the game resets when the players part company.
4.b. Sleep also resets the game.
5 If a hit is issued wrongly then the person who is hit has the right to return the hit
6 Over the years many additions have been made to the rules. These include such things as extra hits for minis, yellow minis, punch buggies(VW beetles) etc. These are not rules of "The Yellow Car Game" they are in fact different games which have been played in conjunction with it.