First, I think the site is great! I just switched from Fuelly and really like the maintenance tracking on mpgtune plus from the other forum posts I've been reading, you guys are really active in the development of the site.
I have more of a theory question/suggestion than a math one:
Maybe I am thinking about this wrong. But it seems to me that if I input a vendor when I fill up, that vendor is getting the last vendor's stats.
I think the Vendors should be shifted up (forward in time) one row.
For instance, if I filled up these three times:
Initial fill up at BP: 14 gallons
Then at Circle K: 12.5 gallons
Then at Marathon: 13 gallons
Really, I used 12.5 gallons of BP gas and 13 gallons of Circle K gas. I'm still using the Marathon gas so I won't know how much until my next fill up.
I'd like to use the Vehicle Statistics > More Details tool to get Fill Ups grouped by Vendor to see which ones were actually the cheapest via $/100mi. Even if a station is historically 10 cents cheaper per gallon but the mpgs are horrible, it could be cheaper to buy more expensive gas that takes me further.
Thanks and keep up the great work!