When I converted my 85 Mazda RX-7 to plug in electric (2010) this was one of the frequently asked questions. It seems like a kind of stupid question because nobody ever asks that about any ICE car because it never does. In the case of the RX-7 I spent about $20000 to make an 80 mile range EV. I got an average of 205 wh/mile (no regen or it would have been better) and before the conversion if I drove in a reasonable manner I would get around 16 mpg around town. With a cost of 12 cents per kwh the $20k investment would actually eventually pay for itself in fuel savings. Using $3 per gallon you crunch the numbers and get 140774 miles to pay off the $20000. In reality it will be less than this because of the lack of oil changes and other service concerns that simply don't exist in an EV. So what about the Model S? After taxes my Model S cost me about $70000 as a pre owned. But I have the free supercharger so in theory I could do all my charging at the supercharger and have zero cost for my fuel. Not even comparing to an ICE my Model S would be paid for by Tesla at 1944444 miles $70000 price / $0.12 (cost of KWH) = 583333 KWH 583333333 wh / 300 wh/mile = 1944444 miles At my current 20000 miles per year average in the S this means 97 years. Better not plan on that. But what about if you compare to a similar ICE car. Things look a lot better. An equivalent ICE which gets about 20 mpg around town and consumes $3 per gallon gasoline vs Model S at 300 wh/mile and 12 cents per KWH (no supercharging). Miles ICE MS Difference 100000 $15000 $3600 $11400 100000 * ($70000/$11400) = 614035 miles and the fuel savings have completely paid for the car plus taxes. For the person who drives 12000 miles per year this is 51 years. If you did 100% free supercharging then this drops to 466667 miles. In my case this works out to 23 years of driving and the car has completely paid for itself. Since I am 62 now I probably shouldn't plan on that working out either. Model 3 will do quite a lot better because it is a less expensive car and the WH/Mile numbers are better from what I have read. Next time someone asks how long until it pays for itself I can say less than 21 years. Yes, it is a silly idea. Doug Ingraham 2013 Model S "The Woman in the Red Dress"