The purpose of asking is to be able to arrest citizens with no intention of committing a crime. Any criminal looking to harm the LEO (the purported reason for this asinine question) would always answer NO.
Answer as you see fit.
I keep a car where the LEO can see the contents of the passenger compartment, documentation is up to date and I have never had anything outstanding. I would never consent to a search, give no grounds to justify a officer safety search and would like to see the reason on a warrant.
"Religions are all alike - founded upon fables and mythologies." Thomas Jefferson
"The way to see by faith is to shut the eye of reason." Benjamin Franklin