You've figured it wrong. After 37500 miles of long-distance driving, you have paid as much as a battery pack. Do you do less than that many long-distance miles in a normal car lifetime?

Your calculations rely on someone paying to swap out their battery every time they run low on electricity. The other person is saying that in typical use, you will end up charging the vehicle most of the time, not swapping the battery.

If you were to swap the battery every time, this would look to be a poor bargain. But if the battery is swapped only once per ten "empties", because for the other 9 it was convenient to charge it, then the calculation would be redone for 10x the distance at the same price.

So, you are both right, but talking about slightly different things (typical use for a commuter with occasional trips, vs long-distance-only users).

The point is that before this, charging (even with a supercharger in ~1 hour) was the accepted method of filling the battery, and it was free and/or cheap. That is still a perfectly acceptable method.

Now you also have the choice of swapping, which provides you with a guarantee of a constantly healthy battery, a fast full charge, and continuous long-distance capability.

I see your point—if you're doing 37,500 miles of long-distance, you're going to eventually pay for the battery cost over time. Possibly. But you have the choice, and it's going to be amortized over so many snap decisions that it's more like, "the convenience of this is worth $40 to me right now," rather than thinking of it as the cost of a new battery.

I think it works out, personally. And for most people, charging is a perfectly acceptable way to drive the car. I think people won't really swap the battery that often, and when they do it'll be because they need the time benefit, and that's the value proposition.

For others, they get the same battery-life and battery-health benefits by swapping only once in a while, or hell, even only when their current battery dies completely. Basically, everyone wins, and it's still about the same cost as gas for a 22mpg car, even if you swap 50% of the time. If you swap less than that, it's cheaper to operate in the same period of time. Simple as that.

Its not at all hard to drive 100 miles in a single trip every week. Visit your brother at the lake. Drive the spouse to a few events on the weekend. Even cruise the shoreline.

So that makes about 7 years (pessimistic) to pay as much as for a new battery pack.

Why would you swap your battery in a 100 mile trip when the model s has much more range than 100 miles on a single charge.

Your new fully charged battery pack, yes. But they degrade. What are you getting from the station? Can you even tell? Pay $40 and end up with a half-capacity battery maybe.

So, use a bigger number than 100, it helps some, but not tremendously.

The max Model S range is 265 miles. That's tremendously larger than 100.