Neither one. It's actually third conversion rate as I mentioned in the my initial post.
To summarize:
1) EPA rating: 326 mi / 72 kWh usable = 4.52 mi/kWh (221 Wh/mi). 1000 real-world miles should in theory require "only 221 kWh" of energy.
2) Supercharger: 2.60 mi/kWh. "1000 miles" used is 400 kWh of energy.
3) Actual driving: ~3 mi/kWh (333 Wh/mi) 1000 real-world miles uses 333 kWh of energy. (This one will vary person to person based on your driving speed, but generally nobody gets even close to the EPA efficiency figures).