Though I'll believe it when I see it in (user) action, this would make a huge difference, IMHO, in the usability of the car. It would make it truly feasible to drive to Tahoe from the Bay Area, for example. That's something I'd pay for.
There is a supercharger at Folsom, so it's totally feasible.
I'm just waiting for a Model X AWD :)
http://www.nytimes.com/2013/02/10/automobiles/stalled-on-the...
So I'm not sure even 3 hr 50 m would do it?