This is a list of modifications done to my phone for reference. Not all may be required. Rooted with TowelRoot (SuperSU), Safestrap recovery installed (with busybox), Xposed framework with Wanam xposed installed (to turn of the emergency call feature on lock screen, disable wake with home button, and disable camera shutter sound), SQLite Editor installed and all AT&T bloatware turned off (make sure AT&T DriveMode is turned off if nothing else).
1. You must have root. If you don't yet have your phone rooted just go to towelroot.com and get Geohot's towelroot app and run it.
2. Refer to this thread (http://forum.xda-developers.com/show....php?t=2720257) for instructions on how to install the DriveLink APKs. This thread references the Note3 running Android 4.4.2 but the same process is used on the S5.
3. Refer to this thread (http://forum.xda-developers.com/show....php?t=2733065) for instructions on how to enable the quick setting tile for Car Mode.
4. Place "DriveLink.apk" and "DriveLinkRemote.apk" on your external SD.
5. Browse to where you placed "DriveLink.apk" and "DriveLinkRemote.apk"
6. install the 2 apk.
7. Open up SQLite Editor
8. Select the Apps tab -> scroll down to Settings Storage and select
9. Click settings.db
10. Click system
11. Click search icon on top right (easiest method to filter) or scroll through db (harder way)
12. Type "notification" in the Filter Value field and press ok
13. Tap "notification_panel_active_app_list" -> select pencil icon on top to edit
14. In Value field, all enabled toggles are listed. Now, add the word "CarMode" (no spaces or quotation marks) to end of list (make sure to have NO SPACES between entries and semicolons separating each entry) (Note: I added a ";" at the end of CarMode as there was one already after the last tile in the list)
15. Once you add "CarMode", click save button.
16. Close SQLite editor and reboot
After reboot you should be able to activate car mode with the added quick setting tile (steering wheel).
NOTE: If car mode crashes at the main screen go to settings -> App Settings -> swipe over to all, scroll down to car mode and select it then click clear cache, clear data, force stop. then uninstall it. After it is uninstalled reboot the phone TWICE then re-install car mode and reboot. It should work after that.
Special thanks to RevelationOmega and ivanjong for doing all the real work!