Garmin Varia RTL511 show false cars (no cars behind me)

the same goes for me. The error came with the last firmware update.

May be the demo mode, varia 510 indoors can also be simulated rear car

I have had very few false notifications on the Varia for the last year and a half. Have you tried it in another area? I wonder if something in your neighborhood is triggering it. I'd call Garmin Tech support. Don't email them. Way to slow emailing.

I observed similar, however this was always around mobile cell towers or other radio technical towers. So microwave connections.

Also your movie is not available:

"

This video has been removed by the uploader"

Depending on how strongly they reflect a radar signal, vehicles, motorcycles, and even other cyclists can all be detected by the Varia Radars. It is common to occasionally see other cyclists (particularly groups of cyclists or riders travelling faster toward you).