Phil Jimenez followed up via twitter with an additional piece of art (right) and comments to fans. I strung them together below.
"Somehow, that rascally @brianbendis got a hold of my JLA/Transformers pitch art! Oh, what an epic that would have been! It would have been EPIC. You missed out on Wonder Woman's invisible jet becoming a very cool Transformer. Another piece of unused art from my JLA/Transformers pitch, with colors by the unbelievable @rfajardojr
"Giving credit where credit is due: the idea for Optimus Prime as a GL was none other than @chris_ryall's. Smart guy. A pitch for a cross-over! Got sideline after the DC relaunch, I think. Would have been fun, though! I'm a sucker for those Seacons. ...this was just pitch art, my friend. Just to give a taste. The transforming invisible jet... which was "female," I think. She would have been sooo cool. This would have been epically fun. No other reason to attempt such a thing, really, except for fun!"