My widget on the Z1 compact was under tools -> then i had a separate widget for GPS. When its off, it's in battery saving mode. When its on, it's in high accuracy mode.
Note, "location" has to be turned on for this to work. If "location" is off, and you press the GPS toggle then you'll be in "device only" mode (and the location toggle will turn back on obviously).
Basically, having the location mode on/off and then turning gps toggle on/off or vis-versa will put you in different modes. Now only if they'd add this GPS toggle to the quick settings....