How to get 2012 Chevy Equinox to recognize my Evo 3d?
On most android phones SD card storage cannot be used by both the phone itself and another device simultaneously. So for the Evo 3d to be available to your Equinox' player you might have to do something like tap on Turn on USB-Storage (not sure if this is your case) or choose Disk Drive when prompted about Connection Type on it. During this time the apps that you've moved to SD card cant be run, neither can you browse the SD card contents from your phone.

BTW, if your vehicle supports bluetooth with A2DP profile, that might be more convenient.