This is intriguing, though unfortunately, a bit out of my hobby budget.
Any evidence at all to back up your assertion that Tesla got each model for half of this price? Even if you are right, though, Tesla has the advantage of buying in Q100,000,000, with the promise of buying many times more over the coming years. For someone buying hundreds of these cells, I haven't seen better than ~$6/cell for similar Panasonic cells, and no telling exactly how new those are. I've been able to pick up lightly used laptop packs with these cells for ~$3/cell on rare occasions, but more commonly such laptop packs are closer to $5-6/cell.
If I remember correctly, curves I've seen on similar cells suggest these would have 100mAh or so more at ~6A. Temperature can also make a noticeable impact on capacity.
I posted some
mediocre notes on a very informative lecture I watched on YouTube called "Why Do Lithium Ion Batteries Die?" by Dr. Jeff Dahn. The video is linked in my post.
His lab has developed a testing method based on a theory of cell aging that seems to make good predictions about long-term cell life based on the results of much shorter tests. The use very precise instruments to measure the coulombic efficiency of cell charging cycles. Li-ion batteries should return one electron in discharge for every electron pumped into them during charge, and any difference is due to parasitic reactions that lead to cell aging and capacity loss.
They've looked at a variety of cell chemistries, under a variety of charging rates and temperatures. What they found is that, basically, the panasonic cells that Tesla uses have low levels of parasitic reactions at "normal" temperatures AND they only increase slowly with temperature. On the other hand, the choices Nissan made for the Leaf's pack were absolutely terrible. Both chemistries they chose tend to have higher levels of parasitic reactions at normal temperatures, and the rate of parasitic reactions for both grows rapidly as temperatures increase. This, combined with the lack of active pack cooling adds up to a sure recipe for premature pack wear.
The other thing Tesla packs have going for them, besides their choice of cell chemistry, and their use of active temperature control, is that they a much larger than the leaf packs, which means that the relative load during typical driving cycles is less.
Time will tell, but I think todays Tesla packs are going to have extraordinarily long lives, and wouldn't be surprised if next gen packs from other manufacturers have considerable improvements in their own durability.