Here is a way I analyzed the new finance to own program that Tesla introduced today. Assume that you get a Model S Performance nicely optioned out at $102,520. Since I live in Washington state, I'll assume a $7,500 Federal tax credit and no sales tax on the EV purchase.
If I put down 10% of $102,520 that is $10,252 out of pocket. I get $7,500 of that back from the Federal tax credit when I file my taxes. So my initial cost in on the buying program is $2,752 (assuming I can get financing for the rest of the balance of approximately $92,268). A loan of $92,268 at 2.95% over 66 months is about $1,516 a month. So 36 months into the loan I'll have $54,582 into the payments and another $2,752 from my upfront payment for a total of $57,335. My actual loan balance remaining at that point in time would be $43,797.
If we assume that the residual value is about 43% of the initial price of $102,520, that means Tesla would pay you $44,083. You could pay off the loan and walk away from the car. But say the car retains a 65% value because of the premium an EV might have because of less risk of engine trouble, transmission trouble, exhaust trouble etc. That residual value becomes $66,638. If I turn in the car for a check from Tesla, I would get back about $22,841 (this is the part where Elon is putting his money where his mouth is, I believe he said on the conference call that Tesla would pay the market price of the car when someone turns it back in). Amortizing that back over 36 months, that would reduce my monthly payment from $1,516 a month by $634 to about $881 a month. Now the WAG i'm making here is in the residual value. But I would think that the Model S would retain more value over 3 years than a conventional ICE.
Then factor in the gas savings or say $100 to $200 a month depending on your driving habits and the mileage of the car you are moving from and factor that into the monthly payment and you are looking at a very interesting proposition for someone who wants to run the numbers and make an assumption that the residual value of the car will be higher than 43%. What if the value is in the 70% range? Then it drives the cost down even more to about $739 a month over the 36 months of ownership (I'm not including any fuel savings in the $739). Very interesting indeed...
(Note, all this applies if you buy the car outside the Tesla program, but Tesla is mitigating the risk on the downside through their program by guaranteeing the residual value)