[benashford]

Apple appears to be banking on software efficiency gains offsetting the reduction in battery capacity. They've done this with various iPhone and iPad releases several times.

But the trouble with trying the same thing for the Mac is the wider variety of software people run on macOS. Third-party software may not have got any more efficient, meaning the battery doesn't last as long.

But if you stick to Mail.app and Safari then, in theory, you'll get the expected battery life.

[jasonlotito]

Except that's exactly what didn't happen. They tested with Safari.

"For the battery test, we download a series of 10 web pages sequentially, starting with the battery fully charged, and ending when the laptop shuts down. The web pages are stored on a server in our lab, and transmitted over a WiFi network set up specifically for this purpose. We conduct our battery tests using the computer’s default browser—Safari, in the case of the MacBook Pro laptops."

CR goes into great detail about their methodology and reasoning for their results.