If not asked, don't tell............Especially about weapons in the car.
Last time I was detained, by the time the leo got close, the truck was off, windows down and papers at the ready...Never was asked about the weapon(s) so I did not volunteer anything...
I got a warning......A good ol Okeechobee County Sherriff motor officer.
That is against the law in many states.
For example it is the law you inform the officer you have a loaded weapon in Lousiana, SC, NC, TX. Failure to do so can result in the loss of your permit.
TN, AL, GA, MS do not require you to notify the officer.
If your going to carry I feel it is a must that you know the laws of the states you are in.