I usually drop 2-3 mpgs during the winter. With all the idling and what not it really kills your fuel mileage.
Install a block heater they work great. I also bought a Katz 300 watt oil pan heater and put on Lund cold fronts on my 02 Sport. I could plug the truck in over night and with in 2-3 minutes of warm up I'd be on my way. Before I installed this stuff, the truck would idle for 10mins.
I don't know about you guys but Dodge truck seem to be cold blooded suckers.
A friend has a 02 Chevy and that thing heats up faster than my 02 with all my stuff plugged in.