Nissan knows and acknowledges that they’re going to have to replace battery packs early, under warranty, in hot climates. (I’ve been in meetings with fleet customers in hot climates where I’ve seen Nissan tell them to expect a 4 to 5 year battery pack life, which is why Nissan is urging them to take the Leaf on a 3-year lease, rather than purchase.) Nissan has done their own financial cost-benefit/trade-off analysis whereby they determined that it will be cheaper for them to replace a few battery packs early, under warranty, in those few hot-climate areas of the country, for those few customers who don’t take the hint to take the Leaf on a 3-year lease rather than purchase, than it would have been for them to design, engineer, develop, and manufacture a sophisticated and relatively expensive active-cooled TMS, especially when most of the country probably won’t need it (as much). (It’s just in really hot climates where the economics strongly favor going with an active-cooled TMS.) For Nissan, it was simply a cold, hard-nosed business decision. There are reasons why the Volt costs $8,220 more than the Leaf.