Has anyone had a look inside the D2 rearview mirror housing, I wonder if there is enough room in there to squeeze in the 801 camera?
Then again it would be a real pain if it has to be taken out for any reason.

Sorry for the confusion. That's partly because I wrote it up some time after installing it. The lead supplied with the camera has a USB connector on one end and a plug to go into the cigarette lighter at the other end. As Andycaca mentions, it has some 5V stepdown circuitry in it. It's therefore not possible to just hardwire it as I mentioned previously. That is where the cigarette lighter adaptor comes in (which I linked to in a previous post), and avoids having to muck around gutting the supplied cable.

The full wiring would be Camera - USB/cigarette lighter lead - cigarette lighter adaptor - piggy back fuse holder. It may not be a very elegant solution, but at least it's guaranteed to work, and only requires you connecting the red wire to the piggy back fuse holder and the black wire to a suitable earth.

So you're not plugging the ciggy adaptor into the cigarette lighter socket, but taking additional cables to a fuse?

Yup.. That's what he's doing.

If I have understood it right he has additional cigarette lighter socket connected to the piggy back fuse and hidden it somewhere, then cigarette lighter USB adapter goes in that socket and USB cable to the camera.

Exactly. Part of the problem for not taking photos during the install, with all the cabling hidden up inside the dash.

Hi All,
I had time to think last night and remembered that I could not find the piggyback that I bought for the job when I fitted the dash cam in my D3. So I damaged a 5 Amp fuse and soldered a wire to one of the legs but made sure that I put that leg in the supply side of the fuse socket. I connected an inline fuse holder to the wire and used that as my cam supply. My cam operates at 12 volts, so I did not need a supply dropper.
The reason I had time to think was because I became stuck on the M1 in the snow. Needless to say I was not in the A8, just a scummy Merc. I stayed the night in a Travelodge near Mansfield, good bed and a very good breakfast this morning.:ROFL:

That will teach you.:ROFL:

Your story reminds me of this.
https://www.youtube.com/watch?v=VAORFjO3cGI

Hope you got home safely.

Arrived home safe and sound Saturday lunchtime. Did two local jobs, and even managed to attend today's (Sunday) Xmas A8 meet at the Leopard.