For what it's worth, the 13-inch MacBook Pro with 2 Thunderbolt 3 ports (this one) gets a hair over 16 hours of battery life in Ars' Wifi Browsing Test. Unfortunately, this benchmark did not contain a measurement for the 13" MacBook Air, its spiritual predecessor. The old 13" Pro got 14 hours.
http://arstechnica.com/apple/2016/11/review-cheapest-2016-ma...