$eose: Thoughts about over-achieving material cost out by 6%:
▶️There are a couple ways that this could be interpreted / calculated leading to different results. (see calcs.)  I can even think of some additional ways to do the math but they get convoluted. 
▶️ Bottom line, the Z3 at scale is 95% material cost and 5% labor / overhead.  Almost all of the opportunity is on the material cost side (which can also be acheived by increasing energy density).
▶️ Even an additional 1% at scale is a massive savings.  At 8 GWh, each $1 of savings per battery would translate into est. $8M.  
▶️ Manufacturing at scale is a game of pennies.  Even a small improvement multiplied across the production volume becomes a very large impact (both postive and negative. )
#eose