I’d mentioned this in the forums in a different context a while ago (at least I think I did), but it sounds like what’s happening to cars around your area is what’s described in this article:
The tl;dr is that there’s a cheap amp that can be placed near the vehicle so that it’s ‘reach’ when looking for the key fob transponder is greatly increased. If the key transponder is within the expanded radius, the doors may be unlocked. This doesn’t apply to push button remotes, but rather the transponders that allow the car doors to magically unlock if it’s very close by and you grab the door handle.
If you’re looking to catch someone at it… you now know a little more about the likely exploit they’re employing.
If you’re looking to prevent it from happening to you, keep your transponder fobs in cheap ‘faraday cage’ pouches.
Here is a link as an example of this type of product - http://www.idstronghold.com/item.asp?PID=285
I’m not endorsing, nor have I tried this product. If you try this or another one, be sure to test it first.
The pattern you mentioned (only contents stolen, not the car itself) fits. The crime still requires the key - it doesn’t ‘copy’ the key, somehow accounting for rolling codes. If it allowed them to start the car, they wouldn’t get too far before they were out of the extended range and presumably the car would not go further… somehow… safely…
Yeah that raises another question. What would happen if one chucked the key transponder out the window at freeway speeds? Anyone want to perform this experiment and report back to me?*
*please don’t do this. I’m curious, but I’m OK being ignorant on this. Unless you already know what happens, in which case, by all means, enlighten me.