The cybertruck is built with the 4680 cybercell. Right now it is actually inferior to the older Panasonic cells from Nevada except possibly on cost. It has 5% less power per weight and size. They should actually be able to get minimum 10% better. That would apply both to the truck and the range extender.  I expect at least 5% improvements in the next 18 months.  That would bring it up to the 500 miles people seem to want.