That depends on three main factors, and several other minor ones:
- How much you drive -- If you drive 1,000 miles a year, you'll pay less than if you drive 50,000 miles a year, all other things being equal
- What you pay for your electricity -- This varies a lot nationally, and often a fair amount within a state. The national average is something like $0.13/kWh, IIRC, but some people pay less than half that and others pay twice as much.
- How much you charge at home -- Some people make heavy use of free charging facilities at work, at malls, etc., and so can get by with little or no at-home charging. Others do the vast majority of their charging at home.
- More minor factors -- These include things like where you drive (highway vs. city), your driving style, prevailing weather conditions (extreme cold and extreme heat both degrade energy efficiency), etc.
To get a rough idea for
you, I suggest you go to the
US DOE Web site, which has a tool to show you the cost to drive a vehicle. You'll need to click on the "Personalize" link to change several factors -- most importantly your annual mileage, the cost of electricity (it's on the "other fuels" tab), and your highway/city mix. When calculating your electricity cost, beware: Most utilities make their bills as confusing as possible. In my case (which I believe is typical), they break costs down into a dozen or so per-kWh categories, then add fixed amounts that everybody pays (in my case, totaling something like $6/month, IIRC). You can get a rough idea of what you pay per kWh by taking the bill total and dividing it by the number of kWh you consumed; but that figure will be slightly inflated for your purpose because it will include any fixed amounts, which will not increase when you buy an EV. Also, if you're on a tariff (rate plan) that varies the rate you pay by the time of day (often called time-of-use, or ToU, tariffs), then you'll want to charge your car at the cheapest times of the day, so you'll need to figure out the rate at that time and use it.
All that said, I just plugged in figures of 55%/45% city/highway driving, $0.13/kWh, and 15,000 miles driven in a year to the DOE site and it spat back an estimated annual cost of $500 for a Tesla Model 3.
One more caveat: The EPA/DOE estimates for the Tesla Model 3 relate to its power consumption when driving; but Teslas are notorious for having high rates of "vampire drain" -- electricity consumed while the car sits idle. These are equivalent to driving anywhere from 1 to at least 20 miles in a day, depending on the features you leave active. At the low end, this isn't a big deal; but if you make heavy use of Sentry Mode or leave the default always-active state for Smart Summon, you could be adding 50% to your electricity costs.