You're right, the model would be improved by adding depreciation. I suspect it would increase the disparity, making the Bolt even cheaper. But I don't know that without looking into it more. I think I will at least look at the topic when I do this again next year. Thanks for bringing it up to me.
There are lots of other things not included in the model, too. I would need to pay a contractor to add a 240 outlet to my garage, which will be like $500 since it's next to the breaker box. I will also spend hours of my life waiting for the car to charge during trips over those ten years. I bet people probably underestimate how much that will suck before they buy an EV. I could include a healthcare cost adjustment due to safety ratings, the impact of which I probably grossly underestimate.
I think the biggest omission is change in the gas:electricity price ratio over ten years. Using current values for the whole ten years is a mistake, considering it's the main difference between the options and is likely to change a lot.
edit: also I'm sorry for the tone of my previous post. I didn't mean for it to sound that way.