The point wasn't that it works out in their favor if they make a ton of trips but not if they make a smaller number. Those figures were approximately a best-cas

The point wasn't that it works out in their favor if they make a ton of trips but not if they make a smaller number. Those figures were approximately a best-case cost for the rental and worst-case cost for mileage-induced depreciation at any point in the depreciation parameter space. If they only added 10k miles then they'd incur $5k or more in rental fees and $1.7k or less in mileage-induced depreciation by the above math. I did misplace a zero though for what it's worth. A budget rental would only cost $500 or so over 10k miles, not $5k, if they're making the entire trip in a single day and returning it to the same place they picked it up. If that's the case the budget rental would probably be worth it financially (unless they were planning to hold the Tesla for awhile so that it hits a more favorable point in the depreciation curve), and if not then the extra rental fees are likely such that especially counting gas vs supercharging it's approximately a wash one way or the other.