[M_a_t_t]

If you have it plot each point as a mpg number (instant speed / instant fuel rate) then average that it would be accurate, but probably the wrong units. It might be easier to have excel convert it to gallons/hr then plot it

I thought maybe all you had were averages, which wouldn't necessarily give the whole picture.

*I didn't look at your pictures since I am on my phone. I will when I get home though In case I missed something.