Superchargers in CA cost $0.25/kWh. The model 3 averages <300 Wh/mi, or $0.075/mi (when charged by a CA Supercharger). Gas in CA is also expensive -- $3.64/gallon in San Jose. Assuming a comparable car to the model 3 (A BMW 335 is 32MPG, and a 540 is 29 MPG on the highway), or $0.11-0.13/mi which is between 52 and 67% more expensive per mile that a model 3 charged with a Supercharger.
If you charge at home, overnight, you pay about $0.125/kWh, which extends the operating cost advantage further.
If you charge at home, overnight, you pay about $0.125/kWh, which extends the operating cost advantage further.