Wow, how crazy is it that every scientific study by Microsoft happens to prove the superiority of their products! What a lucky coincidence, since we all know they would never fudge the results.
They do not make recommendations or conclusions for MS, it is MS that interprets study's results. If looked at power draw, the difference between browsers is small, but IE has an advantage albeit small. Also, the study was done by Kurt Roth of MIT-Fraunhofer Center for Sustainable Energy and looking at the pdf, it shows.
The obvious truth is that Microsoft will only commission a study on something they've already proven to themselves internally. As will every other company on the planet.