This article pertains to Toyota and Lexus, but could be equally applicable to BMW, Merc etc. I also watched a program last year on how the professional car thieves operate across North America to take orders for, and then find specific makes and models of high end autos to be smuggled to Africa and the Middle East.
For $200 USD, they can buy a cheap clone of a device similar to what car dealers use to create replacement FOBs. These devices will read and copy the FOBs internal security codes then clone that to another FOB, then they have another means of defeating the anti-theft software in the car so that they can just walk up, unlock your door and drive away in about 15 seconds.
Keep your FOB away from your front door or garage door, and when out and about, you might want to consider an aftermarket pouch to protect against electronic scanning while in your pocket (if you live in a high-threat area).
https://www.cbc.ca/news/canada/ottaw...tack-1.5380947
https://www.youtube.com/watch?v=bR8RrmEizVg
https://www.youtube.com/watch?v=Di_k2IO83to
https://www.driving.co.uk/news/featu...to-prevent-it/
And don't forget your "hat".