Formula
Each fuel has its own cost per mile. The year is the gap times the miles:
saved = (price per gallon / MPG − price per kWh / miles per kWh) × miles
The result is rounded to the nearest cent. It is energy only. Purchase price, maintenance, and tax are not in it.
Assumptions
- Both cars drive the same miles.
- Prices and efficiencies stay constant.
- A gallon is a US gallon, and currency changes the symbol only.
Worked example
At $0.16 per kWh and 3.5 miles per kWh, against $3.60 a gallon and 30 mpg, 12,000 miles saves $891.43 on energy.
Input definitions
- Annual difference
- How much less the electric energy costs over the year. Negative means it costs more.
- Cost per mile
- The energy price divided by how far one unit of that energy goes.
Limitations
This is a trip sketch. Prices and rates are numbers you type. The currency control changes the symbol only and does not convert one currency into another.
Questions
Does this include the car payment?
No. It compares energy. A loan payment is on the car loan pages.
What if the result is negative?
Electricity costs more than gasoline for the prices and efficiencies you typed.