http://conference.hitb.org/hitbsecconf2017ams/materials/D2T2 - Yingtao Zeng, Qing Yang and Jun Li - Car Keyless Entry System Attacks.pdf & TLDR: YMMV, in a Lexus [& Toyota's] remove and discard the battery in all remotes, use the key inside the remote to un/lock the door, place the remote next to the push button start within 30s [otherwise alarm will sound] to start vehicle, yes, it will start without the remote having a battery in it. Lexus/Toy will not be able to be stolen with above method, if the above is performed, of course tilt-tray and other methods..... I hate push button start/climate control/electric seats [electric chair is ok though] useless gadgets.
So it LOOKS like the scanner has to be within 2m of the key fob....I'm surprised that happens very often. It certainly can't happen at my place. Do many people just drop their key inside the front door though maybe?
