$13.69full charge
The i4 eDrive40 (81 kWh) costs about $13.69 to charge fully at South Dakota's average home rate of 15.37¢/kWh, including ~10% charging loss (89.1 kWh from the wall). That is $4.11 per 100 miles.
EIA residential average, South Dakota, 2026-07 (latest in this book). No South Dakota gasoline series, so this uses PADD 2 regular, week of Oct 5, 2026.
At 1,000 miles a month and 30 mpg, home charging costs $41.13 and the gas car costs $136.97. The EV saves $95.84 a month at $4.109/gal. Both miles and mpg are editable on the calculator.
The listed DC fast-charge time to 80% is 31 minutes at up to 205 kW. A full home charge is a different session. This page prices the energy from the wall, not how long a Level 2 charger takes.
This page uses the residential rate. Public fast-charging prices are a separate scenario and are not included.