Seems to me that it's the same in all cases, whether it's a traffic stop or you're being questioned in connection to a murder: be firm but polite. Don't give out any info you're not required to, but don't be an asshole. Clearly there will be some differences (i.e. you should insist on a lawyer if you're being questioned about a murder, but should not do this during a traffic stop) but my point is that we should not consider a polite insistence on your rights and polite refusal to give out information beyond what's required to be in and of itself being a dick.