If you change injectors and go turbo will the car mpg calculation be correct

With Rebel Turbo stage 2 w/intercooler shows 40 plus mpg at 60 and 37 at 80 but overall getting about 285 miles for every 11 gallons
Trying to keep my foot out for a whole tank but pretty hard to do.
So far mileage range shows 330 plus trip meter total 360 total miles.
Question of the day how does the car calculate MPG

As long as the injector size programed is the actual size used so that its calculating the fuel correctly. If the "tricked" the ECM then it will not read correctly.

okay, i have a 2.2 and i got some 18" rims w/ 235/40's, my mpg went down from like 27 in town to around 23. my cousin said that i could take it in to a dealership and they can reprogram the computer for the size tires i have, is this correct?

My dealer said they couldn't When I had the car tuned by trifecta he made the tire correction. Checked with another persons trip meter to check
over 150 I was 1.2 miles off from a stock car and tires.

My dealer said they couldn't When I had the car tuned by trifecta he made the tire correction. Checked with another persons trip meter to check
over 150 I was 1.2 miles off from a stock car and tires.

i see. well ill check a dealership out.
thanks

okay, i have a 2.2 and i got some 18" rims w/ 235/40's, my mpg went down from like 27 in town to around 23. my cousin said that i could take it in to a dealership and they can reprogram the computer for the size tires i have, is this correct?

Those massive rims and higher rolling resistance will also negatively affect your mileage. It may not be all in the computer.

Those massive rims and higher rolling resistance will also negatively affect your mileage. It may not be all in the computer.

lol massive?
looks like you have stock 18's
thanks though