|Photo Credit: eMercedes Benz|
The specifics of the engine upgrade weren't released but Mercedes did say it was meant as a "tactical" decision to speed up planned developments for the 2016 season. Mercedes are now using their 2016 engine to track test it for the rest of their year. Since there will be no winter testing (engines are homogenized in February, before testing begins), Mercedes are testing it out for the rest of the season.
Within a couple races, other teams not in the championship hunt will start to adopt a forward thinking mentality as well and introduce upgrades to test for 2016.
The upgraded engine relies on a new fuel from supplier Petronas to aid in combustion efficiency. Hopefully we'll learn some more about this fuel-engine duo in the upcoming months.
There's already evidence of this new power unit helping out Mercedes, too. In the second free practice session, Lewis Hamilton and Nico Rosberg were seven tenths faster than third place. As this upgrade is only being used for the works team right now, Lotus, Force India, and Williams didn't fair much better than the usual in practice. However, Will Buxton did report that Mercedes will make these engines available for the other teams by the end of the season.