I looked out today and it was $2.50 a gallon today. If I take my Tesla on a trip, it costs me quite a bit more to use supercharging than it would to take my car getting 33 mpg and drinking regular.
When gas was at $3.10/gallon, it cost me to use the supercharger about the same as a car getting 33 mpg.
Doubling range, unless they doubled charging speed, isn't going to get me a lot. Sure I could ride 2 hours, but then take 2 hours to charge. Now if I could ride 2 hours at highway speed (@ 75 mph) and charge in 30 min, I'd be a lot more interested. I don't see that happening anytime soon given the slow OBC they have now and the cost to upgrade it.