Yes, Adam,
It's called AVC, Automatic Vol. Control. faster you go, car compensates road or wind noise and turns up the volumn via the speedometer reading.
I changed my stereo out, doesn't do it anymore..
Enjoy the 'tunes!
Gerald
p.s. you can control the amount it turns it up by hitting this buttone once or twice. This will put it into AVC #1 or #2, one being more sensitive than the other.