spent fuel - computed attributes

Hi Anton,

Im a bit confused with Computed Attributes for when i want to have report for Spent Fuel.
For example i have a car that i can monitor the distance. so i get the total distance for a period of time
but how to use "computed attributes" for the "Spent Fuel" column.
so for example my car (normative) spent 8 litter / 100 km and i have that actual distance to 120 km.
How will calculate the column "Spent fuel" this issue.

https://drive.google.com/file/d/0BwjjmCE52LjhYThvRmhMV25jdXM/view?usp=sharing

Check following thread:

https://www.traccar.org/forums/topic/help-with-computed-attributes/