Has anyone hard-wired a radar detector into their vehicle? If so, how?
I haven't, but if you are looking for constant 12v power it's a yellow wire running to the dome lights underneath the cover where the rear view mirror is mounted. There's a good ground there too.
For switched 12v power there is a connector under the dash on the driver's side. There are a couple of youtube videos showing how to access it if you look for them.
Gave up my reliance on V1s after the Model S glass blocked radar signals. Haven’t heard if the 3 is any better. Fortunately, no stop has ever resulted in a ticket—11 times now I think; I’ve lost track.
First year's production (Model S) was a problem, but fixed in mid-2013 or so. All windshields after that (S/X/3) have a small area (maybe 4" x 4") on the right side of the mirror where you can use a radar detector, dashcam with GPS or a toll booth transponder. It doesn't have the metallic layer that is used on the rest of the windshield to reduce IR transmission. The metallic layer is what prevents the radar detector from working well. Now common in most new cars as it makes the A/C more efficient which in turn improves range (EV) or MPG (ICE).
TeslaTap - is the 4" x 4" area on the windshield obvious or will it be a matter of trial and error? Either way, that seems like an odd place to mount a radar detector. I was thinking of mounting it in the center of the windshield a few inches up from the dash (so much for that idea).
@jwiner - That 4x4" spot is the only good place (it may larger than that). Anywhere else and you'll drastically reduce sensitivity - perhaps to the level of being useless. I'm not using a radar detector right now, but if you're using the Valentine one (as I did a while back), I used the remote option: https://amzn.to/2W9MRK4 that allows the display/button to be mounter with a better view/access. Worked nice. There are also other radar detectors where the radar unit is mounted in the front grill. These seem to be really expensive and a pain to install.
Sorry - I didn't answer your first question - the area is not obvious or marked in any way. You have to take it on faith :)
I thought it was an area with polka dots on the glass.
@BH - I'm fairly sure it goes lower than the black dots (and the dots were discontinued in 2015 or 2016 for those with newer cars).
The owner's manual has a drawing showing the preferred area for mounting "RFID transponders" to the right of the rearview mirror (p. 145 Dec. 2018 edition), but it doesn't offer specific measurements. I would assume any transmitter/receiver would work best in that location, but I'm not a radio expert, and I don't know how radar frequencies would behave compared to RFID.
My Uniden R3 was hardwired professionally by Calibred Customs in L.A area.