Not much - I find Spanish or Russian to be OK.
When I was stopped I first claimed to be a visitor when the Traffic [email protected] asked me for my ID card, the [email protected] summoned over the Traffic cop and he asked me for my passport - at that point I pretended to not understand much English and the cop simply told me to not do it again and to be off.
Mrs got stopped - as she is Chinese and speaks a Cantopop but with an accent they thought she was a mainlander - started hassling her for her ID which she didn't have on her - started hassling her more for not having ID - then she calls the DH to bring down her ID card (so by now Mrs is speaking English to her maid) - at which point the cop apparently went all nicey nicey and let her go.