In a development Harvard cyber security expert Bruce Schneier calls “interesting” but of unknown practicality, researchers have demonstrated how cellphones can be tracked via their battery usage. The basic principle is that along known routes you can record how much battery is used according to its distance from a cell phone tower.
Here’s a Wired story on it. Key quote:
PowerSpy takes advantage of the fact that a phone’s cellular transmissions use more power to reach a given cell tower the farther it travels from that tower, or when obstacles like buildings or mountains block its signal. That correlation between battery use and variables like environmental conditions and cell tower distance is strong enough that momentary power drains like a phone conversation or the use of another power-hungry app can be filtered out, Michalevsky says.
I guess Tobler still rides!