As expected, Apple has upgraded the M7 motion coprocessor to a new M8 motion coprocessor for the iPhone 6. This coprocessor, which exists separately from the new A8 CPU, allows the iPhone to track movements via continuous measurements from the accelerometer, gyroscope, and compass.
With the iPhone 6, the motion coprocessor’s abilities have been supercharged. With the M8 the iPhone 6 can tell the difference between cycling and running. It can also calculate elevation, thanks to a new barometric sensor, and it can track distances travelled as well.