On a completely unrelated note, it's just occurred to me that with one exception, the primary colours for the wave 4 characters actually do match the drones of Energon Optimus:

Copter-2 (white) - Prowl (white)
Digger-3 (yellow) - Sunstreaker (yellow)
Submarine-4 (blue) - Mirage (blue)

The one exception is Ironhide, who is red, against Fire-1's orange. But Fire-1 arguably should have been red in the first place, and is red in the Platinum Edition release of the toy (though none of the other colours match).

I can't help but think that, given the chest sculpt for Optimus Maximus/Ultra Prime, this must have been intentional.