Wouldn't some of the difference between the ecu vs pump mileage calculations have to do with the fact that the ecu does its math based off of injector duty cycle? Correct me if I'm wrong but wouldn't that be a more accurate metric than the pump which measures to 1/1000 of a gallon (which is 0.128 oz.)? Also I seem to recall a study saying that pumps are often off by up to 1/8 of a gallon per fill up.
Also does anyone know what degree of precision the Ecuador uses to monitor distsnce traveled? Making the assumption that since its a Japanese car and most of the world uses metric it could be safe to say that the car uses kilometers which would be measured at least to the tenth, which would be more accurate than tenth of a mile that you read off the dash.
Just a little food for thought when you see everyone saying how their calculations come in lower at the pump than what the system built into the car will display.
Also if you want to factor in bias, car companies want you to think your millage is better than it is, while gas stations want to wring as much cash out of your pockets as possible.
So if you've made it through my little castle of text the take away is this: I am really speaking out my ass but the truth is never cut and dry, even when it seems like simple division.
Tl;Dr: **** is complicated