It’s that simple. In general, a police officer either needs Probable Cause or Consent to search your car. If they are asking for your permission, that’s a great clue they ain’t got Probable Cause. Therefore, all you have to do is say the magic word, NO!, and they can’t search your car.
Now, you still want to be respectful when you say NO. The police only need Reasonable Suspicion (a lower standard than Probable Cause) to keep you detained for a while. They can pull you over and keep you for hours in the name of they are calling a drug dog to sniff the parameter of your car. But they can’t go inside your car if you simply say NO.
I can not tell you how many cases start off as silly little traffic infractions and then they quickly turn into very serious felony charges all because a driver says Yes instead of No when the cop asks to search. This is not brain surgery. This is not rocket science. Exercise your rights to keep Government out of your life, out of your home, out of your car! Just say NO!