The Tesla Approach to Distributing and Servicing Cars
  In case your eye skipped over the “for free” part, I would  
  like to emphasize that again – owning a Supercharger 
  enabled Model S really does mean free long distance travel 
  forever on our high speed charging network.

I really wish they'd stop saying this. They're essentially committing to building a nationwide electric car charging infrastructure for $nodollars, and never charging customers to use it, ever.Which means either  A.) They're not going to build more than 30 charging stations.
  B.) They're all going to be significantly far away from population 
      centers, and used only for interstate travel.

No matter what, a Tesla car is going to be spending 99.9% of its time charging at home or at work.