In researching something else, I stumbled across this little gem of New Jersey jurisprudence
Consent searches during a lawful stop of a motor vehicle are not valid unless there is reasonable and articulable suspicion to believe that the motorist or passenger has engaged in, or is about to engage in, criminal activity.
This was upheld just recently and extended: "a police officer who wishes to conduct a consent search must have reasonable and articulable suspicion to believe that evidence of criminal wrongdoing will be found in the vehicle before seeking consent for the search." State v. Elders (Lawyers USA No. 9937055) New Jersey Supreme Court No. A-42-06. July 30, 2007. (Emphasis mine).
The occupants of the car appearing “nervous” or “agitated” is not sufficient to breach this.
In NJ, the cops can’t even ask for permission to search your vehicle without a “reasonable and articulable suspicion”. Which is a good thing for NJ gun owners.