Don't ever talk to the cops...ever. It will do absolutely nothing for you. They're not your friends; they're not there to help you. They're doing a job: enforcing laws, however stupid those laws may be, by whatever means necessary.
Reasonable Suspicion
In order for law enforcement to pull you over in a car over they must have "reasonable suspicion" that you committed a crime or are about to commit a crime. "Crime" includes any traffic offense.