I just use an Excel spead sheet it make life so much easier, I put the data onto my spreadsheet at the end of the month I can see my average mileage, mpg, electric and fuel cost, as the majority of my journeys are less than 50 miles, I rarely fill up with fuel, it is only when we are towing the caravan, over the winter because we are not towing last year I went over 4 1/2 months before topping up.
We are Octopus Agile so our electricity follows the market cost, so my energy cost are a moving target I very rarely pay over 16 pence kWh, the majority of the time considerably less in the winter we see a lot of negative prices. This weekend there is excess energy being generated price are negative, they are actually paying use to charge up both the PHEV, the solar storage battery plus power the house, on my spread sheet I just record it a zero cost.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.