When Apple released the 2013 MacBook Air in June, the company leveraged the increased power efficiency of the Haswell platform to provide significantly improved battery life. After spending some time testing the new MacBook Air’s 802.11ac Wi-Fi performance, we turned our attention to power efficiency. Just how accurate are Apple’s impressive claims for the 2013 MacBook Air battery life? Testing Hardware We’re testing an entry-level 2013 13-inch MacBook Air, with a 1.3GHz Core i5 CPU, Intel HD 5000 GPU, and…