If the officer has probable cause, he will search your vehicle regardless of what you say. But if they don't have PC they will ask "do you mind if I search your vehicle" or a similar phrase. Your response to this is "No sir, you may not search my vehicle". Make sure you don't have any incriminating evidence on your person because they are allowed to pat you down and rifle through your pockets. This includes baggies, papers, crutches, or a lighter (that black spot on the bottom where you tamp the bowls? That's probable cause).
It is important to remain calm, and be respectful. Yes sir. No sir. Do not be strident and do not get flustered if the cop acts like a dick.
"Well why don't you want me searching, you got something to hide?" Your response to this question is "with all due respect, I am not required to answer that question." It is also important to remember that refusing a search and responding to said question as such does NOT incriminate you and does NOT provide the officer with probable cause, or even reasonable suspicion (one step lower than PC). Furthermore, police officers may not extend a stop beyond a reasonable time (30 minutes) in order to request a drug dog.
If you are arrested you may request to call someone. It is the officers discretion to allow you to call on the spot or once you're in jail. You are entitled to a phone call. Once placed in handcuffs an officer must Mirandize you. "You have the right to remain silent. Anything you say may be held against you in a court of law. You have the right to an attorney. If you cannot afford an attorney the court will appoint one to you. Do you understand these rights?" Your answer to that is "Yes sir, I understand these rights". If the officer presses for further information, it is imperative to say "I am invoking my right to silence. I will not answer any further questions". At this point, you must remain silent until you are taken to jail and processed. You must answer questions related to booking (name date of birth whatever personal info they require) but you are not required to answer any extraneous questions. During booking it is wise to ask about your phone call, they will tell you when you may make it.
It is important to note that if an officer does not read you your Miranda rights, you have a very strong case against the arrest and charges will likely be dropped. If an officer does not read you your Miranda rights, do NOT tell him you are invoking your right to silence. Just don't talk at all until booking. Remember, the moment you're asked to step out of the vehicle (which would have happened had you refused to allow the cop to examine your papers) you are building a case against the officer and his following (or lack thereof) of proper legal protocol. Remember every detail of the arrest, including questions asked, officer behavior, and especially whether he read you your Miranda rights. It was ruled by SCOTUS that officers MUST mirandize all suspects taken into custody.
I cannot stress this enough: Remain calm, level headed, and respectful at all times. Avoid becoming strident, flustered, or irritated. Do not act like those jackasses on YouTube who sit there and ask AM I BEING DETAINED OR AM I FREE TO GO over and over again. It is only appropriate to ask this question if the officer has ordered you out of the vehicle, no longer has any reason to keep you, and is dicking the dog. At this point you may ask that question.
Finally: preventative measures are your best easiest and safest way to avoid an unpleasant encounter with the police. Be smart, be safe, try not to have your shit on you or in your car. You can reduce your chances of a hassle tremendously by keeping all your stuff in smell proof containers in a sealed backpack and in your trunk. Everything. Papers and lighters included. Don't even allude to the idea that you may smoke anything. Don't keep air fresheners in a visible place either. Keep a few new car smell tree shaped fresheners (idk what they're called but they look like a tree and I think new car is blue or white) taped under your glove box or in the vents. Not visible of course, because a 17 year old with air freshener in their car is something that will make them suspicious. Remember, it is the officers job to find whatever reason possible to arrest you and they will look for the tiniest detail that could possibly allude to you having drugs. They look for signs of drugs during every stop, because it's the easiest way to bust someone.
Be safe.