I find with my tinted glass, my side view mirrors are very dark at night. Are we sure that the sensor is on the rearview mirror? I'd like to cover the sensor to see if that improves my visibility in the side mirrors.

Yes, "we're" sure the sensor is on the rear view mirror (it's the little dot on the surface of the mirror, that's not reflective).

As to whether or not that particular sensor also controls the side-view mirrors, I'm not completely sure.

I just confirmed that it does. Check out page 13 of the pdf.
http://www.bmwmotorsports.org/pdf/e7...%20Mirrors.pdf

According to the manual we can adjust the brightness of the auto dim mirrors by turning the knob under rear view mirror.
But I could not turn the knob. Is it normal?

On a slightly different note, my side view mirrors seem to have a bezel of some sort. There is a 1/4" border all the way around the mirror that is slightly different from the rest of the mirror. Does everyone else have that too? I'm having issues seeing through the driver's side mirror due to some blurriness and seeing things slightly out of focus if that makes any sense. I'm starting to wonder if there's something wrong with that mirror.

The border is the electrical contact path for the gel. Most BMW's have a black plastic bezel, while the X5 and X6 have a thin line. That area will always look distorted. If there's a distortion somewhere else on the glass, just have it changed out (not the whole mirror!) The glass just clips in, and a good tug (warm temperature only, or the plastic clips may break) on the edge will remove it. Then there are two wires for the heating and a locking connector for the EC glass.

That manual has to be wrong about adjusting the dimming. I've never seen an adjustment. The round 'knob' at the bottom of the mirror is for the alarm light only.

FWIW the manual includes instructions for both the 'old style' manual method and the auto-dimming method of reducing glare in the interior rear view mirror. The red knob below the mirror does turn on the manual mirror and tilts the mirror so that most of the glare is reflected up to the headliner. AFAIK this manual adjustment does not work on mirrors with auto-dimming.

Funf Dreisig

Auto dimming interior mirror
 

Any idea how much an Intrior auto dimming mirror will cost? I dont have one as I did not opt for premium pkg :(

Pretty sure it will cost at least $400.

Thanks Funf Dreisig. I will stop bothering the knob then.:D You don't know how many times I tried to turn it.