Windows 8 is more power efficient than OSx Mountain Lion

I just came across the review of the Vaio Pro 13 on Anandtech , i found something very interesting.

The vaio gets less battery than the MBair , there no surprise there because the Air has bigger batteries , but Anandtech normalized the numbers to battery capacity and i got really surprised . ...

The Vaio Pro with a higher screen resolution and windows 8 gets more time of battery per Wh than the Air*, meaning that Windows 8 is more power optimized than Mountain Lion (witch is a big surprise because over the years OSx was always considered to be more power efficient than windows , its really good to see Microsoft improving on that department)

*except in Full load, the higher resolution screen should account for (part of) that.