Car Wars Turning Key

I've been playing Car Wars from Steve Jackson Games sporadically over the years (more then, less now, but still occasionally), and it's going through a bit of a revival now in the run up to a new edition they've been talking about. I thought I'd work up a turning key for it, which could be printed out as necessary and rescaled at will to work with everything from the standard 1" counters to Matchbox cars.

The default scale for this key is, of course, the game-standard 1" vehicle size. The num