My car that gets normally 30-32 MPG in the summer only gets 27-29 in the winter. It's the temp outside, plus the winter gas.

 

I don't know about you but I use my remote start and warm the truck up alot when it is cold so I burn alot of gas in the winter.

 

I just bought a 09 hemi slt 4x4 crewcab.... I have about 1k miles on it. My first 180 miles was a highway trip. I got MPG to 18.4 driving at 68MPH and it would drop down to 16.2 at 80MPH. I eventually quit farting around and locked i at my normal 78MPH and averaged 15.5. Then trip back averaged 15. I make this trip twice per week. Each time My MPG has dropped. I drive 90%highway 10% city baby the hell out it, drive like a damn grandma and now I'm getting 13MPG. WTF! Truck has 1000miles and I went from 18 to 13. Same trip, same gas, same fricken tire pressure 38 psi, only difference is weather is now 5-15 degrees colder in the last week. How can truck drop 5MPG like that for no reason?

I appreciate y'll trying to help figure out why I dropped 4 mpg after the 1k mi mark. I'm now at 2500mi and it's calling for an oil change. Usually I go 5k mi. Do you guys suggest getting it done now or waiting till 5k?

i'm hoping an oil change and some fuel additive will change my gas mileage back some. I'm sure exactly what gear I have. I believe it's 3.9. How do I find out? What it comes down to I drive about 700 mi. per week and 4mpg drop is pretty big. The last three days on the highway I've average 65mph (in a 70mph speed limit) and the truck says I'm averaging 14.1mpg. I reset it, the mileage, the timer (incase they're connected somehow). 14.1 in 23 degree weather. same trip 1000mi's ago I was getting 18.6 (my personal best). If there's anything else you can think of let me know please.

I will post after fuel additive before/after oil change to see if it makes a difference.

I will post mpg after an oil change (which I can't get to for a couple days and another 500mi's). see if it makes a difference.

I'm also going back down a little further south where it's 5-10 degree's warmer. I'll post then as well to see 'how much' the weather affects mileage. I agree with the poster about weather decreasing mileage. I must have an effect as my mileage seems to drop as the weather does. But I'll make sure and chart the differences per degree and post actual results so we all know the exact difference, at least for my truck setup.


09, SLT, Crew, 4x4, not the 20" rims, 2500mi's, i think it has a 3.9 gear, tire pressure is at 38 all the way around.

 

yes. i woud say my biggest gas guzzler would be using the autostart to warm the truck up/get everything closer to operating temps.. now. i cant say for sure but i would guestimate 15 times or more, running at about 10-15min. is gonna eat up some gas. even at idle.


but as a whole i think my "avg" dropped from about an honest 14mpg city (barely any highway) to about 12mpg. city with all that auto starting. so actually im not sure how much worse it would get with me not using the auto start...... (im not willing to try it though!! )

oh. this is in MI. its about 15deg. in the mornings lately. sport 4x4 quad cab 3.55 rear end

 

Heated garage....It's nice..

 

lol. i have a normal 2-1/2 car garage. mine wont even fit! lol.

 

ok just to add a little bit more on to what everyone else already has said... you are in a BRAND NEW v8 truck you will get very poor gas milage from a fresh engine you have to get through that break in period witch can be as much 10-20 thousand miles sometimes to get the mileage you are looking for. so brand new engine+ cold weather=bad gas mileage in big heavy trucks

 

If you have your window sticker still, it will say on the option side of the sticker if you have any other ratio besides the standard 3.55's. Other places where it could be is on one of your axles.Besides that. there was a thread on here where I believe a post stated other places besides the two that I mentioned.Keep in mind that there is no standard location except the window sticker.

 

WOW!! A liter of summer gas goes further than a whole gallon of winter gas?! Daa-yum! I gotta start stockpiling summer gas when I can find it!!

 

I went back to my dealership and my salesman was able to punch in my VIN in some website(not sure what it was) and next thing you know he printed me off a sheet that had all the standard and optional equipment listed for my truck. That is how I found out I had the 3.92.
Maybe go back to your dealership and ask them.