So it has been almost 1 year since I first stashed my AirTag underneath the carpet in the rear cargo area.
@OSS probably hasn't bothered spending the $25, but I'll bet a lot of other mudders have. I would say with good reason. My experience so far has been positive simply because I know that at any time I can look at my iPhone and verify that my car is in my garage. OK...true, I could just walk 20ft and do the same, but I've also done that on vacation and I've done it while my car was at Kelly's in Flagstaff getting a new paint job. I can tell you with confidence that Kelly didn't do a lot of joy riding...
A few months ago I got a notice that said my Airtag batteries were running low. Changing the batteries was an easy job and I can forget about the Tag for another 8-10 months.
My wife and daughter have tags in both of their vehicles. Recently when my daughter came to visit, my wife borrowed her car for a couple of hours. She panicked when later that afternoon her phone warned her that somebody else's AirTag was following her...or words to that effect. She had the option to disable it too...so it is reasonable to expect that a thief will get the same warning if they stick close to your stolen car. But that was 5-6 hours after she first borrowed the car. Remember that 80% of teens these days have iPhone's, so it won't really matter if you've placed it in a zircon encrusted case where the sun doesn't shine.
Oddly, I borrow my wife's car all of the time and have never received a "Airtag following you" notice. She registered it with her phone and her Apple ID and we don't have any family thing going with iPhone...so go figure?
I wonder what is the average time that it takes a person to discover that their car has been stolen? I'll bet about 50% of the time you'll know it within a few hours. Boom! there's your car on a map. Then, for those poor suckers that went to bed with their truck in their driveway and woke up truck-less you will still have a thief without an iPhone 20-30% of the time. And for those clever thieves that did disable the AirTag, a last known location? For the few unfortunate android thieves or those that ditch the car quickly they won't be the wiser for days and days.
Perfect? Well no, but how can this not be a good thing for a measly $25?