Absolutely not.
I have never done drugs, rarely drink alchohol (and have never driven under its influence). I don't own a gun, nor do I ever carry any of my collection of knives or swords. The closest thing they're likely to find in my car to an illegal substance is a can or two of spray primer and/or sealer for my wargaming miniatures. A punk kid is NOT going to pay $9 a can for grafitti paint. I'm sure the foam padded pistol cases I use to move all those miniatures around will cause some concern (especially since there may be as many as 5 in my trunk at any given time), but all they contain is well-painted bits of plastic and metal. I have no criminal record, and have not had a moving violation since the year I received my drivers license (13 years ago). Their reasonable suspicion is nonexistant, and I am well within my rights to refuse an unreasonable search at a routine traffic stop.
In 1998 the US Supreme court ruled in
Knowles v. Iowa that roadside searches for the sake of searching are prohibited under the 4th Amendment. They cited plenty of other instances where a search
is justified, but that if the purpose of the traffic stop was to issue a specific citation (say for speeding or faulty equipment) then the crime at hand is the only one for which evidence may reasonably be gathered. They pretty much said that for a traffic violation, license, registration, and proof of insurance are pretty much all that can be required. They may arrest you if they are not satisfied with the documents provided, but that may only be done in pursuit of the violation at hand (i.e. the reason you were stopped in the first place.
They do have the right to ask you to step out of your car and pat you down for a weapons search but only with a reasonable suspicion that you may be armed and dangerous, and may also do a quick patdown of your vehicle to find a weapon if they have reasonable suspicion that one is readily available.
The court ruled that there is only a remote chance that a detailed further search of a vehicle is likely to turn up evidence related to the violation at hand, and as such the searches are not reasonable. In certain states, even evidence found with your consent may not be admissible against you if there was no reason for the officer to search your vehicle related to the initial reason you were stopped. Once they've got the information they need to issue the ticket, that's where their legal right to investigate your vehicle
ends.
Lack of consent to a search is not probable cause to search your vehicle. There has to be a reasonable suspicion of a serious crime beyond the scope of the traffic stop. You do not have to consent to a search and once the officer requires you to stay longer for the search he has detained you and makes the search without a warrant subject to 4th amendment statutes. It's therefore illegal.
Know your rights, people. They are the only thing keeping us a free country.