I dont know if its just me, but lately with the weather in the mid 30s, I realized that my F is sucking up alot more gas.. I usually average 18mpg mix driving with the F but lately its averaging 16-16.5mpg.. Not a big big difference but it shouldnt be doing that,, I usually run my car for a min or two to just warm it up a bit and drive relatively slow for the first 5 mins to let my oil warm up but overall, I drive alot slower cause of my summer tires still on the car. I shut off the AC too, so is there something wrong with my car? or is it the winter mix in the Gas??

 

It's normal man. See link below for some reasons why.

http://www.hybridcars.com/gas-mileag...s-mileage.html

 

Yup, I also love how my exhaust sounds when its cold out. Yumm...

 

I have not noticed it, but I let my car warm up in the mornings for a few minutes before I take off. So I'm sure I am wasting much more fuel, and likewise I try never to hammer it until the oil temp has 3 bars. But regardless of my OCD, what you are noticing is normal until the engine gets to operating temp it is not as fuel effecient.

 

The elephant in the room here is the engine operates at a set temperature. The bigger the difference between outside temperature and the engine's normal operating temperature, the more fuel you have to burn just to get to operating temp. Combine that with more fuel necessary to maintain that differential, and you've got winter fuel economy losses compared to summer fuel economy.

 

ive noticed my fuel consumption much more rapidly in colder weather, even here in so cal. when i drive it feels like i cant get anywhere close to 15 MPG, which bums me out a little bit. its not like i drive with a lead foot. it could be a mix of simply driving in the cold weather + traffic on the freeway.

 

Exactly how I Feel!! cant even show off how efficient my v8 is anymore... lol

 

I've definitely noticed the mpg drop... (down about 10%) Funny part to me is how it seems to contradict what those wanting to go to the track seem to want: heavier / colder / denser air. I thought that was supposed to be more efficient / generate more power, which in turn would be positive on the gas mileage too... Guess the other negatives more than eliminate that.

 

Ahhh, no, not more efficient. Generate more power, absolutely, but definitely NOT more efficient. You get more power because you get more oxygen molecules per unit volume (higher density), but you also lose some of this gain because the air has to be raised from a lower temperature to normal operating temperature. For efficiency, you want the air just below the autoignition temperature when the piston is completing the compression phase and you want the cylinder, head, and valves all at thermal equilibrium so no energy is wasted heating them - the energy goes into kinetic energy, the cooling system, and out the exhaust. If the engine's components are below equilibrium, they'll take energy from the process to get to equilibrium.

If the engine is operating at part throttle, it's horrifically inefficient for a lot of reasons and colder, denser air isn't making a big impact because you're already removing a lot of heat from the air just passing through the throttlebody (high pressure on one side, low pressure on the other, endothermic action removes heat every time - this is why the OEMs run coolant through the throttlebody - they're concerned it could ice up and stick under certain conditions). The same is true for the intake valves to some extent and their contribution to lower temperatures increases as the throttle opens depending on the intake port's efficiency.

There's more, but it would take a lot more text. I'm not up for it today...