pensioner writes:
/snip
But if he asks and you agree to a search, all bets are off.  You just gave
away your 4th amendment right.

If asked for a search "Thank you officer, but I do not choose to discuss my
personal affairs with an officer of the law at this time, good day".
Politely roll up the window, do not make eye contact, motor away gently.
/snip

JB writes:
Al, I agree with you on the first part of this snip, however, have you ever
been asked by police to search your vehicle?  I've been asked 4 times in the
last 7 years, twice in Missouri, once in Texas and once in Louisiana; the
second time, in Missouri, I refused and posted my experience earlier.  I'd
imagine if you ever refuse anything the police ask, you are looking for
trouble as they will assume you have something to hide and that IS probable
cause.  If I follow your advice in the second paragraph of the snip, I'd
surely find myself in the local pokey and my vehicle impounded.  Yeah, it's
wrong and prolly illegal but not much you can do while sitting in the pokey.
If one motors away from the police, as you suggest, the police will surely
chase you down and slap the cuffs on while they figure out why you refused.

JB -never caught with anything but searched more than I'd like.