Picked up a car at SFO a few days ago. In the lower-left of the windshield was what appears to be an RFID tag sticker.
When I returned it to my local HLE I checked their lot and a few other cars also had them, but most did not.
I'm guessing these might be related to the roll-out of CLEAR (which SFO doesn't have yet) as their mechanism of detecting which car you're in.
