I was looking at a Ford (well, Lincoln, I think) model lately that offered Eco-Boost. I looked at that, and was thinking, oh, they've got a more efficient engine on offer for it. No, it wasn't more efficient; in fact, it was noticeably less so.
But they call it EcoBoost because it's more efficient than the old option for a bigger engine. I guess the terminology must work (for upselling more cars), but it felt awfully misleading to me.