It always seemed to me that they're comparing total cost of ownership of cars, not direct costs of purchasing cars. If it's total cost of ownership, it's an absolutely fair comparison.
But gasoline has nothing to do with the total cost of ownership of a Tesla. If they wanted to have a calculator that showed you the "real cost" of a competitor's car (with gas included) vs a Tesla (with electricity included) that would be a fair comparison.
If I bought a Tesla it would mostly be replacing bus trips not another car. That shouldn't have an impact on the cost of owning a Tesla.
Only if you are comparing Tesla to "not having a car", otherwise gas costs are extremely important.
The problem is, when you tell someone their $30k car actually ends up costing $70k over a few years, they have a knee-jerk reaction (as seen in this thread) - "I don't spend that much" / "Gasoline hardly makes a difference" / "Maintenance costs nearly nothing".
They are basically saying a Model S will affect your monthly budget as much as a $580/month car, I see that as absolutely fair.
They've promised that Tesla owners get free charges from their Supercharger network. The Supercharger network is powered by SolarCity, yet another Musk company. If they're serious about it, then yes, electricity can be zero fairly in those calculations.
