So hot!
 

That's what I'm usually saying to myself when I turn the vent on in the FR-S. Why the heck is the vent air so hot compared to the outside temperature. I've never owned a car where there was this much of a difference. Any way to fix this? I hate turning on the AC if I don't have to, but even today at 73 degrees outside, it feels like 90 inside the car.

So close the vent...

Big problem with our cars.
Air is coming from the blower sucking air from the engine compartment.
Engine compartment is so damned sealed that not much fresh air flows through it making the blower blow hot air into the cabin.
This is one of the contributing reasons why the FR-S has power issues in warmer weather and complicates forced induction applications.

but I like air. it's in my top 3 things I like. just ahead of food and just behind water.

Open the windows? Or, like you said, AC.

Using AC does not affect MPG much, despite popular belief. Use it and enjoy your cold air.

I wish our cars had windows that rolled down. That would be neat.

If gas is your concern there are other ways.
http://www.fueleconomy.gov/feg/drive.shtml

Or just roll down your window like everyone else is saying.

First world problems.

I wish that was true... for the past 2 weeks LA has been quite warm... 90's...

Usually it's like 60-70... and during that time I would get 30.1 MPG.

With the AC on... I'm getting 28.23 MPG.

I stopped driving at 75 MPH (30.01 MPG AC OFF) to 65-70 (28.23 MPG AC ON) in hopes to get better fuel economy.

Checked my tire pressure... I'm sitting at 36 PSI cold...39 Hot.

So from the information gathered from the past 2 weeks... I've noticed a loss of about 2 MPG.

Turn the air vents on full blast, direct them out the windows. Instant +10hp from keeping the engine bay cool.

Or run a CAI pipe directly to the cabin air filter. You could put a BOV on it that went off when you changed fan speed.

I should clarify, rereading the OP, my post is vague.

Using the AC compared to the vent - yes, vent will preserve MPG.

Using the AC compared to rolling down the window - negligible due to aerodynamics. Better to just use AC.

So in summary, you're correct that using AC affects MPG by a small amount (since the engine has to turn the pulley that turns the belt), but when compared to the other solution of rolling down the windows, there's not much of a difference. Our vents suck due to the layout of the parts in the engine, so it's not often we get to enjoy the vents for cooling purposes :respekt:

Hey now. Be nice.