Without googling...At a four-way stop, if 2 cars reach the intersection simultaneously,

[muriel_volestrangler]

60. But you do need a rule for when it is 2 cars arriving from opposite directions

If they're both going straight on, they can both proceed without waiting for the other. If one is going straight on, but the other is turning left, then the one turning left should wait for the other to go before doing the left turn. If they both want to turn left, then either one signals to the other they they should go first, or they attempt to do it at the same time, passing behind each other (which, however, there may not be much room for - it depends on the size of the junction).

It would be incorrect to say "if you arrive at a 4 way stop, and there's no car immediately to your right, you can do what you want at once".

Would you say that a car turning right at a 4-way stop should yield to a car on the right, even if there's clearly enough room to make the turn without impeding that car?