For the last 9K miles I relied on the trip computer/MPG readout in our 2014 Honda Accord EX-L. Turns out it is quite inaccurate. I checked it against my calculation by filling up and dividing distance traveled by the amount of gallons of gas consumed and here are two results:
Indicated 38.3 MPG, calculated 40 MPG over 543 miles
Indicated 37.3 MPG, calculated 34.5 MPG over 458 miles
The second fill-up I drove more aggressively. What does it all mean? Perhaps the trip computer is too optimistic when driving aggressively and too pessimistic when driving smoothly. Another possibility is the electronic measurement is actually correct and my method is inaccurate die to the gas pump stopping when the tank is "full" at different levels.
Still, I finally managed to get 40MPG over the whole tank, with some street and stop/go driving. Nice.