Of the oil consumed by U.S. passenger vehicles, 5.5 percent is used for air conditioning. For today’s average internal-combustion-driven vehicle, air conditioner use results in up to a 26 percent reduction in mpg. For an electric vehicle, this translates to a 36 percent reduction in range.
One way to reduce this cost is to havve solar powered fans drawing in outside air while parked.
Another way is ventilated seats.
Another way would be to design a system where the air con turns on only when the engine is braking or traveling downhill.