Gordon Mah Ung, Macworld, gets to the bottom of the MacBook Pro’s disparate battery tests. Most testers got great battery life, others found it to be terrible. Why? Turns out, it’s a bug:

In looking at other battery run-down scenarios, I ran smack into a problem that’s likely at fault for many of the confusing battery life issues with the laptop, at least in macOS Sierra 10.12.2. On occasion, the laptop’s discrete GPU would just get stuck on and consume power even when it wasn’t used. Others had reported this too, but you’d really have to stumble onto it.

I was able to reproduce the issue in Safari by opening Google Maps, which would cause the laptop to switch over to the GPU for the WebGL workload. Opening additional browser tabs and then closing the Google Maps tab would, on occasion, leave the GPU consuming up to 10 watts of power while doing absolutely nothing.

Terrific job homing in on this. Nothing helps tech support more than a problem they can reliably reproduce.