OK, so i keep hearing that the 3.92 ratio gets better MPGs than the 3.21 in town. Different theories abound so I would like us to hear form others and in real experiences.

I have a way to see if that is true. when you fill up the truck do the following;

1. reset the MPG
2. reset the odometer
3. reset the engine hours

At next fill up, write down all of the three readings. If we divide the miles driven by the hours on the engine, we will get average MPH and with that the MPGs, we will have a good comparison between different vehicles. If we post our vehicle model (CC 2WD or 4WD), engine and axle, then we will have a better idea what's going on.

This is not perfect, but I'm just curious. We will see if this method works when we compare the same vehicles as well as different ones.

And yes, right now I have nothing better to do than be doing this.

 

Engine hours cannot be reset.

 

There is a timer in the tripometer.

 

Also may want to find out if the gearing has been reprogrammed int he trucks computer.

 

Not sure on how you calculating the hours with the mpg but I have a 2010 cc 2wd with the hemi and the 3.55 and I average about 13 around town. The 3.92 is said to get better around town and worse highway, I had the 3.92 in my 07 qc with the hemi and I was getting about the same milage

 

I have the 3.92's and before the larger tires I was getting about 13.5 city and 19 on the highway. With the larger tires city really has not changed but highway now is about 17.8-18. Kind of sucks loosing what little mileage I had. I have 34's now instead of the factory 33's and yes I re-programmed the speedo so mileage is correct.

 

Under about 70mph 3.92 get the mass/truck moving EASIER.Most vehicles I have ever owned with a shorter gear got better mpg in town and at certain hwy speeds.Don't have to work as hard to move the weight.I get 21.4 give or take at 70 with my 1500 on a fairly consistent basis,In town Atlanta 15/16. Low speeds my 03 diesel with 6 speed and 4.10s moves itself effortlessly.Under 1900 rpm I get high teens.Above that low teens.Thats unloaded/non towing.

 

I have a 10' Hemi Crew Cab Sport 4x4.

City: 15.5MPG driving very light footed, if I am driving like an *** about 13MPG.
Highway: 21.5MPG @ 65-70, 20MPG @ 75-80.

 

I was thinking that sometimes we talk about in town milage and highway milage. This makes a huge difference depending on where you live. For instance, I have property in the country with very little stop and go so when I'm driving in town, I'm actually getting different MPGs then when I am driving in Los Angeles with lights and stop signs. Technically, both are in town driving. Same goes for highway driving. When in the country, I can drive 55-60 all day long and get really good milage but in the city, If I am on the freeeway, I speed up to 80, slow down to 40, so it's totally different.
My c5 corvette ha s average MPH indicator and I use it to get a good idea what is really going on. So even thoug I thought I was driving 70% highway and 30% city, the average MPH was around 32. I know it's confusing. Bottom line is, it is really hard to figure out the in town milage.

 

This is why I like the term combined mileage. Even then it does still depend on where you live but over time it should all even out. IMO