That could be debated. The cooler intake charge will make more power than the heated one, therefore may save fuel due to making the same power at less RPM. The difference may be so minute that it is not worth worrying about...
It was always explained to me that the cooler the charge is, the denser the mixture. That molecules were smaller because they were cooler and that allowed more air and fuel into the cylinders and that's what caused more power from a cooler intake charge. So, taking that theory into account, fuel mileage could suffer from a cooler mixture. If all that BS is true.
