^^^^^The "Tune" you get from the factory is a compromise between performance, emissions, and MPG, which of course are all related. It is not the best possible for MPG alone.....IMHO. I am sure it could be adjusted for MPG specifically.
Now whether a company could make any money off such a "Tune" is debatable. The Tune would have to be cost-effective. If it took 10 years of gas saving to pay for itself, I'm not interested. But if the gas savings were sufficient to pay for the thing in say 2-3 years....I am interested.
The word "Tune" as commonly used on this forum, relates to an ECU tuning program.....and is not particularly hardware related. That's the way I see it anyway.
I'll keep my guns, my freedom, and my money.....you can keep the "change".