Using Root Explorer and renaming the poweron and poweroff OGG files worked perfectly, thank you! I'm using Insanity V3 for my Galaxy S4 (tmo) and that was the only part that I didn't like.
I just bought a Lincoln MKZ with MyLincoln(Ford) Touch and I have the Galaxy S4. It didn't work at first, but then I just updated to the new Google Music app they released today and it started working!!! I am going to do more testing, but it's definitely the Android phone that is the culprit...