^ There's a good YouTube video where a law professor lectures a class on why you should never, under any circumstances, speak to the police. It's called "Don't Talk to Cops," and it will change your life.
I've never heard of someone telling a cop the truth like, "yeah, man, I'm not going to lie to you.... I've got a bundle in the glove compartment" only to be showered then with such leniency that they're let go, uncharged.
Nothing really changes, but what does change is that now they've got a statement from you, and that statement is essentially your confession. And even if you don't confess to having drugs in your possession, statements like, "yeah I'm not going to lie, man, we were out here trying to score drugs" (only to have the cop then search your car and, voila, find drugs...)]) well statements like those might as well be a confession.
So yeah, say nothing, and the cop is going to talk a big game like, "oh you can make this so much easier on yourself if you just tell me the truth!" as if you can save yourself -- but you can't lol and at the end of the day, your lawyer will have less options available with which to help you now that you've flapped your gums and all but confessed entirely.
EDIT: It's like when people agree to having their cars searched when they know that they have drugs on them; I always have to wonder what they were thinking. I mean, shit, were they thinking the cop will be all like, "oh ok good you agreed to the search so that must mean you have nothing to hide and so I won't search your car then." lol No... bitch, they're going to search your car and you gave them permission.
If you say no, then yeah, they'll probably still find some reason to search your car (saying no is not in and of itself probable cause, just for the record) but you know what? At least there's one iota of a chance that maybe, just maybe they won't search your car. I'll admit that I haven't heard of it happening very often, but I have heard of it happening, where the cop has just let it go and thought it not worth the trouble.
ANOTHER EDIT: And I think that people just get incredibly anxious and confused whenever they're stopped by the police. If you're not yet under arrest, then you really don't need to be answering any of their questions. In fact, even when you are under arrest, you don't need to be answering any of their questions (you need to be getting in touch with your lawyer).
I'm not saying that you should be rude and/or disrespectful to the police, all like, "bitch, I don't need to answer your questions!" lol but just make it clear to them that you're not a fucking chump, that you're not intimidated by them, that you're not yet under arrest (hopefully) and so you're not all that interested in answering their questions. It can be done respectfully and, done right, I think that it can look even more like you have nothing to hide than if you're entirely forthcoming and honest and whatever else.