There is some truth that the gas is less efficient in winter as Ethanol is added. It actually has more potential energy than gas/petrol, but it depends on the motor. Some do better, some worse.
As far as towing goes, the computer does need some time in, "Hours Driven" to correct itself for best MPG and that happens faster if it is kept in tune.
I don't know if you are using the MPG meter on your dash display or not, but if you are, it is an average of MPG since it was last cleared out. So, it won't react quickly or tell the, "Real-Time" numbers.
Fill up the truck and let the pump turn it off, then write down how many gallons. Do it again and calculate it that way. Unless you already
The dealer is trying to use some truth, but you are right. The cold air is denser and the difference is not going to make it consume 50% more gas. If you went on vacation to the mountains or to an area with a large elevation change from your home, that will make things hard on the trucks' computer as it has to change so many parameters so fast.
Always get gas from a reputable station as the extra cost is worth it. Mobil/Exxon is one of the better ones as they put a detergent in the gas to keep the engine cleaner and they have higher standards for the amount of contaminants in fuel and are very precise with octane ratings. Using the same gas is easier on your Rig as well. The computer does not have to work as much and you can depend on more consistency so the next time your dealer say, "It is that cheap gas you bought one time". You can reply, " No sir, I always use the recommended octane from the same gas station".
Let me know if you need anything else. However, I will be unavailable the next 4 weeks and I will probably loose track of posts that I am working with like this one. You can send me a PM, if it is working, or the team of experts here is a very rare thing. They come from all over the world and we help each other all the time. So, if you can't find me, someone on the team will respond and help you out.
Monday, April 11th, 2011 AT 9:17 PM