Playing across several phones
One phone works well for one car. Two cars travelling together, or a back seat that would rather use their own phone, is a different game — everyone spots on their own device and the scoreboards stay in step.
This is the one that has been planned for from the very beginning: the app was built from day one with the seam in the right place, so phones can talk directly to each other over the local connection rather than through anybody’s server. Still no account, still nothing that needs a signal.