Why? The Model S has a full range TMS and liquid cooling for the battery, including the ability to hold the pack below ambient at high outside air temperatures. There is probably a range of outside temperature in the middle where passive cooling is more efficient, but the car's systems can clearly handle more heating or cooling load than that - and in that limited temperature band the car would just be passing more heat to the radiator through the cooling pumps it is running anyway if you insulate the pack. By the time you get to temperatures where the insulated pack needs air conditioning, the uninsulated one will too - and you'll reduce the required air conditioning load by having the insulation.As far as I can see the only downsides to the insulation are the cost, weight, and aerodynamic impacts, along with any effect it has on accessibility/serviceability - a well designed installation should have minimal impact to all of these, and will reduce both heating and cooling losses substantially I would think.Walter