The decisions all boil down to space. You say there's plenty of room, but that's just not the case. We have to handle a wide range of data in those places. Odometer readings can run six digits. Currencies around the world can have a per-unit price that runs six digits. So we're very pressed for space in both places and we need to make decisions about what to show there.
The Log Book is about your latest fuel economy numbers. The odometer reading is incidental to that. It doesn't tell you anything about your fuel economy—it's just a number. Your trip miles show the distance you went which tells you more about your fuel economy. You need to know the distance and the fuel volume to get your MPG or L/100km for that particular fuel-up. So the Log Book is reflecting the most relevant data you entered for your fuel economy.
Since I also track my data in my own spreadsheet, it is cumbersome to go back through the data I've entered via Fuelly Mobile via the Fuelly Log Book. I have to edit each entry in order to copy&paste the precise number of litres to the 3 decimal places that I've entered since this also doesn't appear in the Log Book nor the Fuel-Up Log - it's only 2 decimal places.
You say the space is tight, I say you need to do browser detection and have a more dynamic page display. Fuelly on a widescreen monitor, which more users have than have not, is a frustrating layout comprising mostly cream colored background with no data whatsoever.
For litres, you could display 3 decimal places just like price/litre using the slightly smaller font size that price/litre uses.
I'm just saying that if you could detect more about the user's browser environment, a much more useful data layout could be made.
You say the Log Book is about latest fuel economy numbers but I don't use it for that. Selectable Log Book columns would allow me to select the data that's important to me.
Most annoying is you persistence on the issue of web page space. I don't like the usefulness of a web layout to be constrained by the minority of Luddite PC users with antiquated monitors.
How about making the Recent Activity right hand side column optional? With this turned off, more room could be made for real pertinent data. I really don't care when other random users fill up their vehicles.
Thanks for your feedback. There's definitely more than one way to design a site. We'll give this some thought.
Just start off each fuel-up note with the odometer reading...that's my work around for this issue that allows me to see the odometer reading as I scan the notes.