Here's what happens when your Tesla Roadster (or any EV) reaches the end of battery life

Just read it costs $15,000 to have a Tesla model S battery replaced at the dealership. List price I'm guessing. Life expectancy is 8 to 15 years. [Say 12 year average]. So 12 years times 12,000 miles per year = 144,000 miles. 144,000 miles divided by 25 MPG = 5760 gallons. 5760 gallons times $3.75 per gallon = $21,600. Plus plugs, set of wires, three 12 v batteries, trans oil and filter change, approx.. 30 oil and filter changes for the engine.

So, assuming both ICE and battery powered vehicles run trouble free, the money saved on gasoline vs. electricity will pay for a new battery installed by the dealership. And then you get to start all over again.

You forgot to include the purchase price of the vehicle.

And you assume you will be able to get a new battery for your model of EV after 12 years.