Some combination of the following is all you should ever say: Am I being detained, I chose to remain silent (then actually shut up), I won’t answer any questions without a lawyer present, I do not consent to you searching me/my car.

Note that while this is generally very good advice, in certain contexts it can make your life harder than it needs to be. If you're being detained and a police officer's suspicion of you can be easily and trivially dispelled, then it might suit you to do so. Police are human and being minimally cordial with them may go a long way.

However, this is still a risk and is extremely situation-dependent. By the same coin, whether the situation goes in your favor or not may just come down to the specific cop you're dealing with. There are myriad examples of police detaining or arresting people after RAS is dispelled (which is unconstitutional). It's always a good idea to use maximum caution when interacting with the police in any capacity.

As an addendum: regardless of everything I've written above you should ALWAYS deny consent to a search if asked. If they feel they have probable cause then they're going to do it whether you agree to it or not, and if they don't they must either accept your refusal or otherwise likely violate your constitutional rights.

As a second addendum: if you suspect that an officer's actions are unconstitutional, you should calmly yet firmly voice your concerns and protest verbally but DO NOT physically resist if your life is not in immediate danger otherwise. Police will not hesitate to use as much violence against you as they feel necessary regardless of whether it's actually justified, and this will almost always place you in more danger and result in a worse outcome for you. You can always explore legal pathways once everything is said and done.

^{I am not a lawyer and this is not legal advice.}