What's your advice on consenting to a search of your car? If you refuse, are they likely to use his as reasonable suspicion to go ahead and do it anyway? And what restrictions are there on searching, I remember someone saying once that there were some limits to what they could do in a search without a warrant.
Know your rights! They cannot have reasonable grounds purely on the basis that you have declined the request to search the vehicle.
If you consent, you've consented. They can and will go to town. Searches must be recorded in writing.
One of the main things to remember, as previously stated, is that if you have pissed them off, they will find a pretext to search your car. Simple as that. This goes one of three ways -
1) You have nothing and they've slowed you down and demonstrated how l33t they are
2) You have something and they fuck you right up
Here's one which is reserved for those who have been smartarses and despite knowing you're up to something, they can't prove it.
3) You have nothing... and from somewhere, something tiny and cheap but very legally damaging, such as a single round of .22 ammunition, appears in your car in plain sight. Amazing! Your day is now REALLY getting ruined.
Here's a case study on refusing consent to search.
Police member, having gone through all the usual formalities after licence checks etc: We'd like your permission to search this vehicle. Do you consent to that?
Person A: Whaddya wanna look in me cah for brah?
Police member: Do you consent or not sir?
Person A: Git fucked brah yarnt searchin nuffin
Police member: Sir, you're becoming abusive, exit the vehicle now
Person A: GIT FUCKED YA FUCKIN PIG CUNT FUCK!
Police member reaches for pepper spray. Fade to black
Now, let's have a look at another case study
Police member: We'd like your permission to search this vehicle. Do you consent to that?
Person B produces mobile phone or microcasette recorder and hits record: No, I decline to consent to you searching my vehicle. Please provide your name, registered number, rank and station details, as your are required to upon request, before we proceed further.
Police member, extremely shocked, complies
Police member: May I ask why you decline?
Person B: If you had any legitimate reason to search this vehicle, we wouldn't be having this conversation, would we? I decline your request for consent to search.
One thing you must keep in mind - being in a high crime area without a plausible excuse, combined with prior history, may well be reasonable grounds to search. Never push your luck if you can avoid it.
[EDIT: Chopping out the last sentence; keep your advice to personal possession. If people are moving things of an "amusing nature" regularly, BL is not here to help them. hoptis]