Red Bull's route to preparing for 2016 was fraught with indecision over its power unit.
It is invariably a team that leaves a new car's completion until the last minute anyway, so expect the RB12 to change a great deal over the two weeks of testing.
The car has shown some of its secrets so far, but there is also evidence that Red Bull is holding its final specification back to maximise development time and exploit all possible gains in the windtunnel.