Oh crud, I can see what happened now. These latest details ARE the ones I used for my estimates.Based on this, I calculated a volume of 0.962 L, and so I expected close to 2 kg per cell.
This is a very different set of dimensions, only about 3/4 of the length and 3/4 of the height (and similar thickness): 149 mm x 40 mm x 98 mm is 0.584 L, so 1.23 kg is entirely reasonable (2.1 kg/L) and the 100 kg and 20 kWh totals make sense. The total cell volume is only 47 L, an easy fit in the available volume and reasonably packaged in four rows like that, presumably either with each row staggered back from the one below it or in a rectangular box leaning back, to match the seatback angle. Of course interconnects, structure, enclosure, and any cooling system will bulk it up, but it should still fit.
I'm not sure why the supplier assumes only 144 V / 40 cells = 3.6 V/cell, since most lithium-ion chemistries other than LFP run up to 3.75 VNOM, but it might just be a difference in assumptions about voltage at 0% and 100% SoC due to different charging practices, and the resulting nominal voltage. Samsung SDI specifies 3.68 VNOM.
Those cells are so small that they could almost (but probably not quite) run in a stack down the console under the shifter and parking brake as Duncan suggests, although only about half the wheelbase is available and that would only accommodate only one-third of the required cells.
When I responded a few days back and quoted 200x37x130 I was looking at the wrong row in my spreadsheet. They weren't the ones I used for the estimate. Hence my totals did not match the cell dimensions.
So sorry for the confusion and resulting effort.
The 200x37x130 cells were one of many other options I have considered to some degree. They were LifePo4 105ah (2.02kg) and it was looking more like a single set (45s1p) at about 91kg and 15kwh.
But again I don't really have a firm choice for cells yet. I am a good 12 months possibly 18 months away from needing them.