Read my post #6 were I prove it DOSN'T. Pleaser feel free to offer proof it does but I have shown it doesn't at least in my Model 3. If if DID work it has been removed for some reason. Maybe it is a bug that removed by accident and not known but it is NOT there. My test is conclusive.
Why no Dynamic Speed Sensitive Volume Control???
Engine noise is almost never a factor at 70 to 80MPH. It is wind/road noise. I will measure today but bet the noise floor will be about 70dB at 80MPH on a smooth Interstate surface and and is comparable with most newer premium cars. This is why I choose 80dB white noise as my test level. Will post back later today.
Perhaps the speed sensitive volume is "always on" at a higher volume than the one you tested at? Someone also said "glaring oversight about navigation not turning down music volume while its speaking directions"... but I think it actually does do that if I remember properly... if the music volume is high enough.
Since you are going through the effort of testing, maybe try testing at a higher volume than you did.
No argument from me that it should be user selectable. I am in the camp that always turns off speed sensitive volume for reasons others have already gone into, but if it exists, it should be user selectable.