This will go into a spreadsheet where the averages will be calculated as a whole and for each "type" of car.
Please do not duplicate your entries or overlap them. i.e. if you drive 100 miles, enter it, drive another 50 miles, the second entry should not include the Wh/mile of the first 100 miles.
I have made the date fields required to help prevent overlap entries. The #Number and Dates will be used as the primary key for entries.