Compare charging cost to gasoline price

I would like to request a TeslaFi added feature. I want to easily compare my charging cost to the equivalent gasoline / diesel price for the same mileage. There would be an input in settings for the gasoline price in the person's area (similar how there is an input to electricity cost in a person's area). Then, on the calendar page, there would be another column for the month calculating [ (TOTAL KM / CHARGE COST) * (GAS PRICE $ / LITER) ] ^-1 * 100, giving you equivalent liter per 100km.  A similar calculation could be done for MPG.