Tracking a value against a baseline in a graph

Hi there. I am looking for some advice.

I have a private lease car which has a limited number of kilometers allowed under the contract.
The car itself has been integrated in HA, and I can read out the odometer.
What I would like to do is track the actual odometer reading versus the projected value based on the month.
Example: contract started July 1st, 12000 kilometers allowed per year, odometer should not be above 2000 by September 1st, if that makes sense. How can I for example create two graphs, one with projected kilometers and one based on the actual odometer reading?

Thanks!

The only way I can think of doing this directly in HA is to create a new sensor that tracks how far you have driven and resets every month to zero. You can then create another sensor that updates every day by taking the amount so far this month and projecting where it will be at the end of the month at that rate. (E.g., based on how far you are through the month.) the you will need to use a third-party graph tool to plot into the future.

-David