The Tesla S hype has me interested. So now I’m curious, what does it really cost to run per mile? The Tesla site has a decent calculator, here’s some numbers derived from it.

Tesla says they get 283Wh/mile. Electricity in San Francisco costs $0.35/kWh. So that works out to $0.10/mile in a Tesla. Tesla compares itself to 22 MPG cars. Gas in San Francisco is roughly $4/gal, so it’s $0.18/mile in a gas car. By that math, a Tesla is roughly half the cost of a gas car in San Francisco.

San Francisco has outrageously high electricity costs. At the national average of $0.11/kWH a Tesla is more like $0.031/mile, or six times better than a gas car.

On the other hand, batteries wear out. Tesla is offering to replace the battery after the 8 year warranty at a prepaid cost of $10,000 – $12,000. Assuming 12,500 miles a year that adds $0.10/mi to the cost of driving a Tesla, dwarfing the cost of the electricity! The Tesla ends up being $0.13 – $0.20 / mile compared to $0.18/mi for the 22 MPG gas car (and roughly $0.12 – $0.20 / mile for gas cars in general).

If you think of the battery as another form of “fuel” that needs replacing every eight years, then the Tesla costs about the same per mile to drive as a gas car no matter what electricity rates you pay. But maybe the battery will last longer; no one really knows. Also, I suspect most Tesla customers think of the battery cost as depreciation and not a consumable.

Another argument for Tesla is that electricity is somehow more environmentally friendly than gas. Not really; a Tesla is metaphorically spewing 44% coal emissions out its tailpipe. It's 20% nuclear though, I think that's a win.