Not sure if this is posted elsewhere, but here you go. Wonder if it will come to Model S/X in the future?
Tesla adds hidden payment option to buy ‘Supercharger credits’ in kWh blocks ahead of Model 3
Tesla Model 3 'Supercharger Credits' discovered on 'MyTesla' page
Tesla adds hidden payment option to buy ‘Supercharger credits’ in kWh blocks ahead of Model 3
Tesla Model 3 'Supercharger Credits' discovered on 'MyTesla' page