It's likely a metal-air battery, gets installed in the "frunk" (right under your nose), combined with higher power SuperCharging (1.5 or possibly 2C), you end up with a 1,300 mile range in 15 minutes - a typical ICE car would need 2 or 3 fillups to accomplish that. The one time use metal-air pack replacement and water are sold at vending machines, located (you guessed it) at the SuperCharger locations.