A gallon of gasoline contains about 135,000 BTUs. A KWH contains about 3400 BTUs and costs about a dime. Thus, there are about 4 bucks worth of electrical energy in the energy in a gallon of gasoline. The Tesla will be somewhat more efficient that a gasoline vehicle, but certainly not excessively more efficient. Since electricity costs more than gasoline, but the electric car is more efficient, figure they offset each other, and the operating costs will be a push.
So, a vehicle that gets 20 mpg traveling 60 miles will burn 3 gallons of gasoline that produces 405,000 BTUs of heat energy. That is the same energy as 118.7 KWH of electricity.
Now we get into the murky area of relative efficiency, because the auto uses, what, about 20-25% of its heat energy to move the vehicle and the rest is just dumped out via the radiator. But electric vehicles are not 100% efficient either, for at the very least there is energy lost in the recharge cycle.
In any case, it is useful to work through a real-world example to get to the point were it is shown what immense amount of energy it takes to move a vehicle. No matter how we provide that energy, it is not a trivial issue. Our energy needs cannot be met by a pair of D cells, no matter what environmentalists from a parallel universe believe.