I had one the other day around dusk. I saw a car moving pretty quickly behind me at a distance so I moved over to the right lane than as he was about 500ft behind and to the left my RD goes off, but not full alert. As he passed it kept alerting me warnings from scatter awhile after he passed me, 1/4-1/2 mi away. I never got a full alert, but i do have a 9500I.
I figured he just left his radar gun on and sitting on his seat, but who knows?
It was a brand new off white unmarked impala with tinted windows. So I was thinking what would a brand new impala be doing with K band?