I just bought a 2021 Prius (Limited) to replace my recently totaled beloved 2005 Prius. On my squashed Prius there was a trick to (IIRC) put (red?) translucent film over a sensor on the rear view mirror, and to rotate the mirror 180 degrees. Do I want to do this on my (not yet delivered) 2021 Prius?
"In a Gen 2 Prius, you can turn the mirror upside-down so that the sensor gets a better view of oncoming headlights."
"If you look closely, you can see it has a photocell facing forward, and a photocell facing rearward. It compares the brightness forward (so it doesn't dim as much when it's light out) to the brightness from the rear (so it dims more when stronger light falls on that cell). If you put some partially light-absorbing film over the front sensor, it will tend to dim more, or you could put the same stuff over the rear sensor, and it would tend to dim less."
I guess gen 4 still has the split-view rear window with the spoiler across it, so it could still have the issue where the shadow of the spoiler falls right on the mirror sensor and keeps the mirror from dimming. Whether it often works out that way, geometrically, for your height and typical distances other cars follow behind you, might just turn out to be one of those things you'll find out after driving it some.
