Did you ever get any answers to this question? I have an '08 V and I'm seeing the same thing. On my Pontiac Solstice the speed sensitive volume works really well. When I slow down the volume drops and as I accelerate the volume goes up gradually so that the music is always loud enough to hear. On the VLR it's just kind of all over the place, and it seems to jump around while I'm driving at a constant speed.