Total gallons used?
Personally I'd like to see a box in the "basic stats" area with the "total gallons used". That running total is used in all kinds of your calculations but we're not seeing it.
2008 Toyota Prius Touring purchased 04/2016 at 101k miles, currently at 186k miles
2009 Acura MDX purchased 12/2019 at 159k miles, currently at 194k miles