WTF is wrong with you?
A 2012 Mustang and you want to defile it?
Do you want more mpg or are trying to save money? Buy a Prius.
Pick the right tool for the job. Do you want a fun to drive car, or a high mpg commuter?
Buying a NEW Mustang and then 'ecomodding' it makes no sense.
Poor car.
I understand people going crazy ugly on old cars that they have owned for years, but a NEW muscle car?!? Should have sold it and bought something that worked better for your application than try to adjust the one you have.
Flame away.