Cold weather = bad gas mileage?

[TwoTalons]

You ever notice how much higher your idle speed is when you start your car in cold winter weather as compared to when it's warm in the summer months?? More fuel used. It takes more fuel to warm your car up in the winter than in the summer. I guarantee it. Your coolant may be coming up to operating temp in the nearly the same amount of time, although I don't see how that's possible, but that doesn't mean your engine and everything else attached to it is fully warmed up yet.

The fluids in trannys, xfer cases, and rearends gets thicker in the cold. Until those fluids warms up, they're adding parasitic loss to the drivetrain. This all adds up to more fuel consumption. One of the nice benefits of synthetic fluids is they don't get thick in the cold like regular dino oils & lubes do. I remember having conventional fluids in one of my DSMs and parking on an incline in the winter. After sitting overnight in near zero degree temps, it would not roll back in neutral. It was like I still had the parking brake on. After switching to synthetics, it was like releasing the parking brake.