18 mpg Dodge while towing?

I've never calculated the MPG I get towing my 15,000lb 5th wheel but I'm sure it's near 20 MPG....why is my nose growing???

azdryheat wrote:
Friend claims 18 mpg while towing 35' toy hauler with 2003 Dodge Cummins Diesel with manual transmission. He says he never goes over 55 mph. Is he for real?

I have a same '03 Dodge/Cummins NV5600 305/555 HO 3.73 axle 2wd in a 2500 short bed quad cab truck.

19 mpg while towing a heavy TH ???
...could be a single best tank using the short fill method.
....... watching the fuel guage and guessing at mpgs.

A '03/'04 305/555 Cummins HO does get some of the higher mpgs. Mine has averaged 12-12.5 mpg (pencil figures) over several tanks on long trips pulling my 11000+ lb 5th wheel trailer.

I'm not saying he is getting 18, but the 2002 and 2003 were noted as being the best for fuel mileage on the Cummins. Add to that that he has a stick shift and. Does 55, it could be pretty good. When we did the upper peninsula trip this past summer one of the guys we were with was getting poor mileage on his mh with a 440,dodge, so we slowed down to 55. Wow! What a difference. My mileage went from my normal 10 mpg, to near 13. That is a huge difference. Now the question is, when I'm on my own can I travel that speed for hours? Probably not, but speed does kill the mileage.

My stock 2010 F150 pulling my 4000lbs loaded off-road POPUP trailer will make my 429 mile trip from King George VA to Gatlinburg TN on one tank of gas. This is a totally different situation however with almost ZERO wind load from the POPUP trailer. Actually when we go without the trailer we almost do the same thing haha...

I will Gas up when we hit NEWPORT TN and head on in to ELKMONT CAMP in the Smoky Mtn Natl Park. Run around town for three to four days and use maybe a half a tank. Then Gas up again at Newport TN for the return trip back to King George... Thats in the 19-21 MPG I'm guessing - Never really calculated it...

When my son-in-law follows us down with his older 2004 Dodge Truck pulling about the same weight with his high wall POPUP trailer doesn't do as good as my F150 does.

Roy Ken

I word with someone that claimed his Tahoe MPG average didn't change much when he towed and he was sure he got 18 when towing. Towing 100 miles won't change the average much if you have 100,000 miles and never hit reset.

He`s probably not resetting his overhead computer. it averages, so if he drives it empty most of the time then tows, the computer is still showing his unloaded average. it would take almost a thousand miles before it gets close to the actual towing mileage without resetting it!

Best we ever saw on a run of over 100miles was 16mpg...

Of course, we dropped from 6500ft to 1000ft in a mostly long steady drop and we had a 20mph tail wind most of the day and that was only a 28' unit.

Long term average for that truck was a little under 13mpg towing.

Not unless his tow hauler is light-weight and has no frontal area. I get 12-13 depending on terrain. Unloaded I get 23-24. Yes that is hand calculated.

Especially if the dashboard mpg is "instant" mpg instead of averaged. Go downhill, mpg could jump to 50mpg. Also he may have "hand calculated" mpg once under ideal conditions, instead of calculating on a regular basis to once again get an average mpg.

My buddy has a 2006 MegaCab 4x4 Cummins. We take turns towing his bowfising boat. My Duramax gets 14mpg hand calculated. His Lieometer says he's getting 26mpg. After doing a trip in his Cummins hand calculated we came back with 14.2mpg. Most inaccurate gauge I've seen on a truck.