Disappointing highway fuel mileage

I've had this 2015 2500 for approx 9 months now, 12k miles on the odometer. Most all of my driving is around town and towing. Just yesterday we left for our family vacation so we got our first true highway miles.

Drove from Maryland to Pigeon Forge, TN with most of the miles down RT81. Drove between 70 to 75 mph on average, not any higher. Cruise rpm was right at 1650 rpms. Had the cruise set on when I could.

Trip odometer said right at 500 miles till we pulled in, low fuel light had just come on. Filled up and hand calculated which came up with 19 mpg.

My old 2003 would get 20-21 mpg on highway...and that was with 3.73 gears, shorter factory tires and probably turning 2200 rpm at 75 mph.

Also, I sure wish Titan would offer a larger tank for the short bed crew cab. I kinda miss the larger tank my old trucks long bed had.

 

You are complaining about getting 19 at 70-75 in a 6.7?? I either missed your sarcasm or am confused.

The truck has so many more emissions controls on it. 19 is great for that speed.

 

19 MPG is about 2 MPG better than my 2011 gets at the same speeds when not towing. The 2011 with 4.10 gears gets about the same mileage at 70-75 MPH when not towing as my 2002 ETH/DEE 3500 dually did with 4.10 gears - about 17 MPG.

Rusty

 

No sarcasm.

The new truck runs the exact same fuel mileage around town as my old truck. Given the taller tire, different gear ratios and less rpm logic to me says it should get the same or better highway mileage even considering the new emissions equipment. We're talking every bit of 500 rpm less at the same speed from new to old.

 

On modern engines with the level of fuel control that we have, and the quality of machining/components, I don't think you will find that much of a difference in rpms.

Additionally at lower rpms the engine has to work harder to make the power. It is all a tradeoff. 3.42's and taller tires means less torque to the wheels thru multiplication which means more torque needs to be made at the engine for the same load, and the truck is likely heavier.

All in all 19 at 70-75 with a 6.7, one that may not be fully broken in yet, is nothing I would complain about.

 

More emission controls, more power, heavier truck....mileage will suffer.

The best mileage my 2015 2500 has achieved is about 18 mpg, and this was only once. My normal, commuting mileage is about 15-16. Coming from a gas motor, I'm tickled pink.

 

This was my thoughts also.

 

And speaking of larger fuel tanks. I was looking at the 2015 or 2016 and found there is no larger replacement tank available from Transfer Flow...... the DEF tanks and other stuff makes it impossible.

I can't have an in bed tank as i haul a truck camper. Love my 60 gallon replacement tank on my 2011.

 

I'd be jumping for joy at 19MPG on my 2011. My old 2005 never got 19 unless I was doing under 70.

 

TransferFlow have not developed one yet. Titan makes a 55 gallon replacement tank that supposedly fits fine per a member on here.

 

Your 19 Mpg at 75 is right on target. if you drop your speed down to around 63-65 you'll see your Mpg go up. I get around 21-23 if I behave. If your really not in a rush try 45-58 I was able to get 27-29 mpg on a few tanks while driving down in the Fla keys on Us1. Speed increases the wind restance which kills Mpg.

 

#ad


Well we made the next leg of our trip. Drove from Pigeon Forge, TN to Nashville.

I dropped the cruise control from 70/75 mph down to 65 mph.

I don't believe the dash so I will hand calculate in a few days when I top off to drive home.

Fuel gauge sitting on 3/4 tank. Should have taken the pic in landscape mode instead of portrait.

#ad

 

Had trouble loading the image off my phone. Not sure why it wound up turned sideways.

 

That's better than I get unladen in my 2007 5.9.

 

It's a shame I couldn't have ran a whole tank full on that run before switching over to down town driving. I found with my old truck the computer would show high mpg early and then slowly taper down as you drove through the tank of fuel.

 

I was initially disappointed in my fuel economy of my '15, when compared to my 2nd gen....then I weighed it and realized these new trucks are ALOT heavier than the "old" trucks.

 

Yea, especially when someone adds 2' of steel to their rig:-laf

 

Touché. Haha

 

Yea, I guess I never gave anyt thought to the heavier weight.

 

Well maybe I need to change the name of this thread. lol

Went through the second highway mileage tank of fuel. This time with the cruise on 65 instead of 70-75 as mentioned before.

Stopped to get fuel before the fuel light came one...

562.8 miles
24.91 gallons
22.59 MPG (dash was showing 23.6 mpg)

Not so bad after all.

I also found my notes on truck weight and towing capacities. Truck per RAM is rated at a curb weight of 7650 lbs. Traveling this trip with 4 family members and a bed full of suit cases, food, etc. Truck also has a cap (approx 200 lbs), so it's safe to say the truck sits at 8500 lbs easily.