Short trips: engine oil, diff oil, trans oil, etc is cold so more friction, less mpg. When averaged out over a tank, dramatically affects the mileage, nowhere near spec.

Slow-speed, stop-and-go driving, with an automatic: the torque converter is not locked-up, slipping is occurring expending energy/heat into the trans fluid. Again, dramatically affects mileage.

Ethanol content of the gas you use: I notice a 3% - 4% mileage increase when filling up with Shell vs Esso, Petro Canada, or other less common brands (Southern Ontario). My theory is that there is less ethanol content. One day I will test this with my aviation fuel tester tube thingamajig... This is also a factor between winter and summer - my theory is that the gas companies have a different additive/ethanol mix in the winter that helps prevent gas line freezing (ethanol absorbs water).

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2011 Supercab Sport 4x4, 4.0L, Auto, 3.73LS.

Theory.... No theory there brah. Thats a fact. In winter, the expy get about 12mpg. In summer, 19.

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Ball Joints/Upper A-Arms How To
Replace Door pin/bushing
Repair broken dome light tabs
VIDEO OHC Install

Cold air is more dense than warm air. The computer knows this. As temperature decreases, fuel flow increases. It has to in order to maintain the correct air/fuel ratio. This is a huge factor in fuel consumption in the cold weather. It is also why you feel like you have more power in cold weather and are dragging ass on a hot summer day. More air and fuel in the cold = more power.

<< Sent from my iPad, so you can hate me on this too >>

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(Formerly)
FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: 300+ intake threads here on FRF
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide