My 2 cents:
1Tb hard drive does not equal 1,000,000,000,000, it is 2^40 = 1,099,511,627,776.
I think Tesla has said that they don't use the 18650 cells, they have Panasonic modify it a bit. Not sure if they do anything capacity wise to it, doubt it, but just throwing that out there.
WK is...