I see leases as having three primary functions in today's car market:
- Tax treatment: Depending on your tax situation, leases can be expensed, which can be advantageous relative to ownership.
- Put option: At the end of the (open) lease period, you have the imbedded option of returning the car or keeping it. This option lowers the transaction cost of selling or trading in a used vehicle; it also allows you to dump a lemon back to the car company (or the leasing entity) at an above-true-value price.
- Manufacturer incentives: Many car manufacturers set up lease terms at below-market rates as an implicit price discount.
Tesla isn't interested in #3, and #2 isn't compelling
for Tesla either, in part because there's no really good way to ensure that the driver has taken appropriate care of the battery (although I'm sure many drivers concerned about the longevity of Tesla Motors would like this option). The tax treatment value of a lease, though, is real.
I expect that, as we get closer to Model S shipping out, we'll see some entities offering Model S leases; I'm betting, though, that the terms could be horrendous.