Yeah, I understand what you're saying. We set it up this way because we wanted those "Best Tank" notes to be a rare event that you want to achieve. We didn't want them to be an everyday occurrence. I hear what you're saying about precision, but I think that would take away the feeling of accomplishment of hitting another milestone. It's not all about technical accuracy. Yes, technically .1 MPG is better, but lowering the bar would take away the feeling that you're accomplishing something. Getting 1 more MPG is not easy.
The problem is that you can improve your mpg several times by 0.9 and not have anything register, even if the 5th time you have improved by 4.5mpg which is worth celebrating!
I quite understand why you don't want the notes for best tank which appear in the sidebar, but I was actually talking about alerting you to the fact that it is your best mpg in the check calculations window after your fuelup. This would only appear to you, but as your fuelups increase in number, the size of improvements in mpg will become less frequent and smaller.
It is kind of like world records for 100m sprint. Nowadays, records are broken by hundredths of a second.... But they are still records.