If making HP is your goal cooler air makes sense, if MPG is your goal it doesn't.

If you introduce cooler air (even a few degrees) the engines computer will richen the fuel mixture (the cooler the more it will richen). More O2 means you can burn more fuel, less MPG but more HP.


Steve

 

My 2012 FX2 5.0l w/ 3.31 axel ratio is a flex fuel motor (I think they all are). I have been running 87 octane since day 1 and I have 4000 miles on her now. My cruising MPGs at 70 are 19.5 to 19.8 and every tank average has been 18.1 or greater. I got a half tank of E85 yesterday and I am 80 miles into the tank now with 25 miles around town and 55 on the freeway. My cruising MPGs are down now holding at 18.3 to 18.5 at 70. The motor runs very smooth and my butt dyno tells me it pulls a bit harder. I would need to put it to a stop watch to verify this. Just a quick FYI for all.

 

I was getting 13 mpg on my 2008 f150 xlt. Added flowmaster dual exhaust system, K&N cold air, tonneau bed cover, and performance chip, improving my mpg to almost 18!

 

New 2013 F150 Ecoboost Lariat Crew Cab 4x4 331 gears with 600 miles- 14.7 mpg short city driving. 19.2 on 20 mile highway run @ 70+ mph. I am sure as it breaks in it will get better.

 

This is my mileage with 4x4 on and -10C

 

The ECU will dole out an air to fuel ratio of 14.68:1 regardless. Cooler/ denser air will just allow better utilization of the fuel.

 

Yeah... That's metric. Pretty depressing if you move that back to MPG instead of Liters per 100 Km. (13.75 MPG).

 

06 crewcab 4.6l 3.55 gear. I drive 23 miles one way to school so 45/46 a day. I'm unemployed right now. I get 16 gallons a week from my dad to go to school. I would drive at about 75 mph and it would suck everything I had. So roughly 235 miles a week. About 14.5 mpg. I wasn't a heavy foot going anywhere just fast highway speeds. Then it got $4.85 a gallon here in so-cal I started driving at 55 still at 16 gallons a week. Driving at 55 I would have more fuel left over every week to where I was able to get half a tank at the end of the week. I calculated I was saving close to 3 gallons a week. I know this isn't a good way to get accurate mpg but just by dropping 500 Rpms mpg raised tremendously. Oh yeah 30 gallon here

 

95 f-150 (302) Eddie Bauer gas milage is decent

 

I agree, I never drive over 70 Mph (2K rpm) as my mileage sucks if I go over it.