This question asks how you should respond to a police stop, and one of the answers sited what I believe is common wisdom, ie "be co-operative".
This got me thinking - what are the advantages of being co-operative, rather then being non-responsive except to the extent you are obliged to be - ie simply not answering any questions you are asked (without explaining why), while still following lawful instructions (eg handing over your papers when asked, getting out of the car if instructed etc) ?