I've got no reason to have an ego in this matter and I understand your frustration. What I'm trying to get across is that you will get a new engine if the excessive consumption causes your current engine to fail.
I will go so far as to say you're stressing yourself out and possibly causing undue stress to others while dwelling on a situation that will either remedy itself or be remidied after repair (or engine replacement). You get loaners, you aren't left walking, and your car is being look at. In reality your gripe should be that the loaners you're getting while they're trying to figure your car out are costing you because they aren't as efficient.