Or they just got one of the 'good' models and tuned linux a bit. I have a couple lenovo's and its hit/miss, but my 'good' machine has an AMD which after a bit of tuning idles with the screen on at 2-3W, and with light editing/browsing/etc is about 5W. With the 72Wh battery that is >14h, maybe over 20 if I was just reading documentation. Of course its only 4-5 if i'm running a lot of heavy compile/VMs unless I throttle them, in which case its easy over 8h.

One of my 'bad' machines is more like 10-100W and i'm lucky to get two hours.

Smaller efficient CPU + low power sleep + not a lot of background activity + big battery = very long run times.