content: Before Washington even had this idea this was already going to be mandated nationally on cars made after 2022 or so. It's not tied to your license plate but correlating it is easy enough. "The US National Highway Traffic Safety Administration (NHTSA) is proposing a requirement that every car should broadcast a cleartext message specifying its exact position, speed, and heading ten times per second."  The RF broadcast would be on Channel 172 on the 5.9 GHz band at ~15 dBm (the minimum suggested) to achieve a 300m range. The purpose would be to aid autonomous vehicles. These cleartext messages sound like they'll be signed with a rotating set of some ~tens of keys as a basic protection against some kinds of spoofing. The dangers of spoofing a system (ie, GPS or this) used by autonomous vehicles to plan routes is obvious. The dangers of yet another source of location data may not be. It can be argued that people have already given up on not being tracked everywhere due to the prevalence of tracking smart phones (both software/gps and basestation/multilateration) and of license plate readers and their databases. But at least those things are mostly optional. Mandating this broadcast on all cars is a major change even if the range is nominally only 300m. ref: https://www.gpo.gov/fdsys/pkg/FR-2017-01-12/pdf/2016-31059.pdf - The RF bits start around page 32. ref, summary: https://freedom-to-tinker.com/2017/06/21/killing-car-privacy-by-federal-mandate/ It sounds somewhat similar to an already existing NHTSA creation: the tire pressure monitoring system (tpms) that already exist in some vehicles/tires. These signals can uniquely identify a vehicle and can be received with $8 dvb-t usb sticks used as software defined radios (rtlsdr) and decoded using https://github.com/merbanan/rtl_433