The cited Carnegie Mellon study was based on the Saft VL41M Li-ion battery cell that has a specific energy after charge of 136 Wh/Kg. All costs of the Li-ion batteries in the study were on a weight basis. The BEV240 case vehicle was modeled with a 66.1 kWh battery pack. So, the weight of the Li-ion cells in the BEV240 would have been (66.1 kWh) * (1000/k) / (136 Wh/Kg) = 486 Kg.
The Model S's Panasonic Li-ion battery cells have a specific energy after charge of 240 Wh/Kg. Doing similar calculations, the weight of the Li-ion cells in the Model S's 40 kWh battery pack would be 167 Kg; the 60 kWh Battery Pack, 250 Kg; and, the 85 kWh battery pack, 354 Kg. So, the BEV240 case vehicle's battery costs overstated the Model S's 40 kWh battery pack costs by 191%; the 60 kWh battery pack costs by 94.4%; and, the 85 kWh battery pack costs by 37.2%.
Also, with all of our electronic gadgets, there is an enormous amount of battery R&D at this time. Li-ion battery manufacturers are projecting annual energy density increases of 8-10% for the next several years. If we follow the methodology of the study and base all battery costs on a weight basis, we could possibly see battery costs decreasing fairly rapidly & for the Model S, this is starting from a much better cost basis than BEV240 case vehicle.