You do not have to allow a police officer to search your vehicle after you are stopped.  Officers can be tricky in trying to get your consent.  They may ask if you have anything illegal in the car, and when you say no, they might suggest that you don’t have any reason not to consent.  Don’t fall for this.  Most all law enforcement officers wear body cameras.  Be polite but firm and tell the officer you do not consent to a search.