@Ivan
I didn’t know the EX-T came with a manual. Is yours a hatchback?
It mostly affects engine responsiveness. If you have a heavy foot, it won’t save much. I get better mileage than my wife because she accelerates harder and skips using cruise control.
I turned it on in my grandma’s CR-V, and her mileage went from 25 MPG to about 27 MPG.
My Si doesn’t even have Econ mode 
I used to deliver pizzas in different Hondas. I turned Econ off and actually got better mileage.
Econ just smooths out throttle inputs and adjusts the AC for efficiency. If you drive gently, it won’t make much difference.
Yes, it reduces fuel injection and adjusts the air conditioning.
Only use it on highways. Otherwise, it’s not worth it.
I’ve found it does improve my mileage a bit.
I guess it helps a little.