I think it'd be reasonable -- for more than just cheating reasons -- to make your scanner move at, say, a maximum of 25mph. So if your "actual" location is, sa

I think it'd be reasonable -- for more than just cheating reasons -- to make your scanner move at, say, a maximum of 25mph. So if your "actual" location is, say, 50 miles from your last location, but it's only been an hour, your scanner is disabled for an hour. That would probably disable most "war-driving" strategies, while making most (but not all) legitimate strategies still available. And, I think that war-drivers probably detract from the game overall. Or you could choose a higher maximum speed if you wanted to -- 40mph (as the crow flies) would probably only disallow cheaters for the most part, though it might disable your scanner for several hours after a plane flight.