Back to the original statement about extending battery life by turning off mobile data. That's very good battery life, no question there. The battery sucking culprit must be the cellular data function, not the GPS receiver. Android phones have always been able to use GPS in airplane mode to extend battery life. Beginning with iOS 8.3, iPhones also have this feature. With both operating systems, airplane mode now leaves GPS on, and provides the option to turn on WIFI and/or Bluetooth.