Apple claims a 10 hour battery life on the 2016, and 9 hours on the 2013 for both the wireless web and iTunes playback tests. Judging by the Comsumer Reports tests though, they would get a shift of 6+ hours from test to test on the 2016 model.
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.
"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.
Is it apples to apples?
iTunes test is less controversial.
But "the 13-inch model with the Touch Bar ran for 16 hours in the first trial, 12.75 hours in the second, and just 3.75 hours in the third" seems to dramatic to be due to hardware -- here it seems something kept some CPU's at 100% in the last case or something like that?