[jeff88]

Originally Posted by ChazInMT

In the case of a cold air intake, the only effect on something that affects MPG would be the throttle position and thereby pumping loss. The energy required to drag air between the restricted opening that is caused by the throttle plate is what causes a decrease in engine efficiency. So anything we can do to make this restriction go away by opening the throttle helps, anything to close it hurts MPG. Warm air intakes increase MPG's by supplying less dense air, which contains less O2 for a given volume to the front of the throttle, in order for the engine to supply the required power for a given load, the throttle must open a bit in order to supply enough O2.

Conversely, a cold air intake supplies denser more O2 rich air, requiring the throttle to close a bit.

The OP mentioned people with CAI having increased FE on the highway. Are you saying the CAI is not a reason for that and only the more open throttle plate is the reason for the increase?