So, thanks for all your input. It was clear that the graphics-only version of the chase rules wasn't cutting it, so I've gone back to the text plus graphics style of One Page.
Even so, the One Page format forces simplicity on the rules. So, instead of the "roll to lose sight" in the text incarnation, now it's just a flat number - the randomness and excitement come from the chase procedure itself.
An extended ruleset would cover things like tracking and listening after losing sight, but an aware enough GM can handle that kind of thing ... right?