Here is how you get your cost per mile for the EV you are researching to buy or already own.
Gather the kWh / mile rating for your EV
First, go to fueleconomy.gov and look up the ## kWh / 100 mi for your chosen EV:
You’re looking for the “## kWh/100 mile” rating. In this example, let’s say 29 kWh/100 mi. So 29 kWh / 100 miles = 0.29 kWh per mile.
Gather your cost per kWh from your Utility
This part will vary depending on your energy provider. In this example we’ll use San Diego who has SDGE as a provider and EV-TOU-5 as a plan, so we would search for “TOU-5 SDGE” and found:
https://www.sdge.com/residential/pricing-plans/about-our-pricing-plans/electric-vehicle-plans
This page on our utility’s website has accordions that open up and show the cost per kWh for peak, off peak and super off peak hours. If you use CCA (Community Choice Aggregation) it’s a bit more complicated because they separate the delivery and the generation charges. For this example, let’s look at the non-CCA option “SDG&E Electric Generation and Delivery”. Super off peak is currently 13.0¢ / kWh.
Calculate your EV’s Cost per Mile
Now you have everything you need to calculate your cost per mile if you charge only during super off peak hours at home.
$0.13 * 0.29 kWh/mi = $0.0377 per mile
That’s $565 per year if you drive 15,000 miles a year
Supercharging Cost Per Mile
Supercharger rates can be calculated as well. Around San Diego today rates are $0.51 / kWh peak rates mid-day currently as of 6/7/2024.
$0.51 * 0.29 kWh/mi = $0.1479 per mile
That’s $2218.5 per year for a Tesla Model Y LR RWD for 15000 miles if you drive 100% on superchargers at the peak rate of $0.51/kWh. This is the worst case scenario and it’s still much cheaper than gas for a Model Y size SUV. As a comparison, a Subaru Crosstrek uses 0.037 gallons of gas per mile. At $4.63/gallon the Subaru Crosstrek costs $0.17131 per mile or $2569.65 per year for 15,000 miles at 27mpg.