At $3.00 per gallon the break even point is about 10 years (one image and a brief excerpt below):
You can see for yourself that at $2/gallon gas it would take 15 years before the Model S made up for its initial cost. However, at $3/gallon itÃ¢â‚¬â„¢s 8-9 years, at $4/gallon itÃ¢â‚¬â„¢s 6-7 years, and at $5/gallon the costs are nearly identical for the first 5 years. ItÃ¢â‚¬â„¢s worth noting that in all cases, after you make up for the initial cost of the Model S, the savings really start to pile on
Gas will probably go up to more than $3 per gallon over the next 10 years.
Good luck on getting a replacement battery pack for $4k.
I'd never purchase a car made by a company run by the founder of Paypal (don't need pals like that).