Gas vs. Diesel

I just got back from our maiden trip with the new 28RKSB WC, 4000 mile round trip to YellowStone and S. Dakota back home to S.Texas. I'm pulling our WC with a 2007 GMC 2500HD with a gas 6.0L engine, I averaged 7.9 mpg towing over the entire trip, the lowest was in West Texas 109º into the wind 6.3 mpg, the best in Wyoming 9.5 mpg. The truck had adequate power on the interstate's and flat roads, but could have used more power at higher altitudes and long grades up mountain passes. I'm trying to justify the increased cost of buying a diesel truck, but I'm curious if a diesel will give much better fuel mileage while pulling and solo, or is it about the same, I understand the power is going to be much better, also my truck only has a 26 gal fuel tank and stopping every 150 miles to fuel up got old pretty quick. Any comments on actual fuel mileage while pulling your WC would be appreciated. I'm guessing our WC weight at about 9200# loaded.

I have a 2008 Chevrolet 2500HD crew cab short bed 4x4 with the duramax diesel. I get about 9-10 mpg towing my 32QBBS. It was getting old stopping every 180 miles with the stock 26 gallon tank so I added a RDS fuel tank / tool box that gravity feeds into my stock tank. I now hold a total of 77 gallons of diesel and have greatly increased my range

I saw where GM is putting a 36gal fuel tank in the 2011 2500HD Crewcab Short bed trucks, it about time they figured that problem out.
Thanks for the info, I also found a replacement tank made by TransferFlow, but at over a $1000, not sure if I want invest that much into a truck I may trade if I can justify a new diesel. By the numbers looks like you are getting 2-3 mpg better than mine.

General knowledge is that the fuel economy of all 2007 and newer diesels is not as good as diesels built before 2007 due to the emissions controls. I do believe the newer diesels are still better then gassers economywise. There is no comparison when it comes to diesel power, though. My cummins was built in late 2006 so it does not have all the emissions stuff like the newer diesels. My combined gross weight (truck and 5th wheel) is just under 20,000 lb and I get 12 - 13 mpg consistantly with the cruise control set at 62 mph (100 km/hr). I have a 34 gal tank and usually refuel at between 300 and 350 miles.

When you purchase a Ford with an 8 ft. bed, you get the larger 38 gallon fuel tank. We also added a 74 gallon in bed axillary tank. Even with all that extra weight, we get around 13 mpg when towing the WC at 60 mph. This last trip across the country, we increased the speeds to 70-75 mph and the fuel mileage fell to 10 mpg. Empty at 70 mph we still get 18 plus mpg. The new 2011 Ford diesel trucks get somewhat better mileage do to Ford using a taller rear gear with a much more powerful diesel engine. With 105 usable gallons of fuel, we have a range of over 1000 miles, which gives you many more options on where and when you fuel up.

I get 10-11mpg with my old truck towing around 65-70mph. It'd be better if we didn't have all these mountains around here. I can drive around 350-400 miles per tank. The lowest mpg I saw was 9.2 when I was fighting a head wind for a few hundred miles. Truck only I average around 15mph in town. I don't do much highway only driving empty as the trailer is attached for trips.

For comparison, I'm usually around 21,500#.

Also, I can pull 6% grades and maintain 50-55mph. I know you can't do that in a gas rig.

Maxtor wrote: With 105 usable gallons of fuel, we have a range of over 1000 miles, which gives you many more options on where and when you fuel up.

Don't forget your low profile/low rolling resistance tires too.. (Maxtor's truck)

That's a nice setup Maxtor. I'm considering a Ford or GMC, I had a bad Dodge truck experience, so not really interested in a Dodge truck

There is simply no comparison of towing power between gas and diesel. I never realized how dramatic the difference is until I purchased my 07 classic Duramax.

We recently towed our Cat over 1150 miles to the OBX and back. Crossing over the Appalachian Mountains each way. We averaged 12.1 MPG towing and 19 MPG empty while there on the flat lands of the island.

These were hand calculations. The trucks computer showed a little less than what we were actually getting.

I'm leaning toward the GMC Duramax, mainly because of the Allison transmission, and I tend to buy GM products. Although the Fords look mighty nice too. I'd be tickled pink to get 12 mpg towing. That alone would justify the difference in cost between a gas truck and diesel truck

Keep in mind that diesel costs alot more at the pump. That being said, I will keep my Cummins which gets 12.5 averaging 70 mph pulling the 13k Cameo. Odd thing is that I only got 12 pulling the 9k Wildcat.

Brad, it's the wind resistance/drag, not the weight. On the hills, the weight matters. My old Prowler weighed 7k and the WC is 12.5k and I get the same mpg. The Prowler had a blunt front with a slight angle. The WC is a lot taller and has a smoother nose. You may have a slightly better nose design on the Cameo.

I have had both and agree that there's nothing like the power of a diesel. I have only towed once with the new V10 and got 7.22 mpg but figure that will go up some after i get a few more miles on the truck. I did have a 2005 6.0L PSD and the best i ever got towing was 10.5 but i always had my foot into it (hate being last in line)

So far i'm not sorry i went back to gas, i figure i can buy alot of gas by not having to spend an extra 8 to 9 thousand dollars for the diesel option.

I get a consistent 10mpg with my 32qbbs and no wind. Throw in some good old south dakota winds and the mileage suffers greatly. I pull at 70mph for the most part and if I could ever bring myself to slow down a little I know the mileage would improve. I have the 38 gal tank and that is a nice comfort not having to stop very often to fill up. I would say maintenance cost are more with the diesel than a gas, but I could never give up the power and torque, especially in the hills. I would love to trade up, but the 07 and newer fords have had some mileage issues. I am waiting to see how this 2011 stacks up and may pull the trigger in the near future. I hear the mileage has improved and they have a new transmission that is suppose to be a dream....time will tell.

Four words GO WITH THE DIESEL you will never regret it...

I to am going to exchange fuel tanks for a 48 gallon tank next year, I can't believe that GM would put a 26 gallon tank in a vehicle built for towing...

With our 6.0 and the 29 RLBS. weightiing total 18,500 lbs
it gets 14.5 mpg average. It does not make a difference in the mountains or on the flatlands of the tidewater.

jetskier wrote:

Maxtor wrote: With 105 usable gallons of fuel, we have a range of over 1000 miles, which gives you many more options on where and when you fuel up.

Don't forget your low profile/low rolling resistance tires too.. (Maxtor's truck)

I forgot about this picture...
But it did work, getting the truck low enough to drive into the garage while I was recuperating from my hip replacement surgeries. I still have those wheels and tires in the other shop. The difficult part was when I wanted to remove these wheels and tires, the truck was so low, I could not get a jack in the lifting points of the truck, so I had to drive up on 2x4 blocks to get it high enough to get the jack under the truck. (in the front)

I would not have anything other than a diesel to tow with. We just got back off a 4700mi trip through the west, mileage was 12 driving 65, up hill and down. New 6.7 would accelerate from 65mph up any grade we found. 38gal tank would get over 400mi between stops if not in mountains.

Thanks for all the reply's, looks like I'm sold on a diesel, now the hard part all I have to do is decide what flavor.

I think you have already solved that problem. If you are comfortable with GM products, than that is what you should look at.

talala wrote:I would not have anything other than a diesel to tow with. We just got back off a 4700mi trip through the west, mileage was 12 driving 65, up hill and down. New 6.7 would accelerate from 65mph up any grade we found. 38gal tank would get over 400mi between stops if not in mountains.

What is your rear gear ratio? Tom and I have been looking to trade up to the new 6.7 Ford, but found that we could only get 3.31 gears with srw and that was a non-posi differential for the XLT. We are looking at a XLT because you can buy it with cloth seats. Leather seats are not fun in hot climates. 3.31 gears seems very high. cruise rpms would be very low, especially towing here in California at the legal limit of 55 mph.

Have 3.55, comes with camper pkg, also have the electronic lock diff. 18" wheels.
Has much more pulling power and better economy than my '05 6.0l which also had the 3.73 like yours.

talala wrote:Have 3.55, comes with camper pkg, also have the electronic lock diff. 18" wheels.
Has much more pulling power and better economy than my '05 6.0l which also had the 3.73 like yours.

The problem is, that the King Ranch comes only with leather seats,,, no cloth.. The xl and xlt are the only ones that have the cloth seats,,, and they only come with 3.31 differential, per both Ford dealerships we talked to in Maryland and California. You would think that Ford would want to sell trucks, so they would be more flexible and let us build the truck we want with the interior and differential we want. 3.55 also seems high... what are your rpms in overdrive at 60 mph? Here in California, where the speed limit for towing is 55 mph,,, chp normally will not stop you unless you are ten miles per hour over the speed limit,,, in this case 65 mph... So most of us tow at 60 mph. If you tow at the speed limit of 55 mph,,, you become road kill

Here is a neat video of the new GM HD trucks:
http://www.youtube.com/watch?v=4zwHWrxmvNk&feature=player_embedded

Specktout wrote:Thanks for all the reply's, looks like I'm sold on a diesel, now the hard part all I have to do is decide what flavor.

If a supplier discount for a GM product will help, let me know. I will get you one.

John

We just made the trip from Michigan to Dallas Oregon with our unit(see signature). I was surprised what power the 6.0 produced. Gas mileage is a different story. We considered a duramax but couldn't justify the cost. We're satisfied with what we have.

Maxtor,at 60mph my rpm is <1500>, if you order the camper pkg you get 3.55 rear end.

talala wrote:Have 3.55, comes with camper pkg, also have the electronic lock diff. 18" wheels.
Has much more pulling power and better economy than my '05 6.0l which also had the 3.73 like yours.

Sounds as if you like the 6.7. I just ordered one for a company rig; F350, chassis cab, 6.7, 3.55 electronic locker. Can't wait to try it out; however, my personal truck (7.3) is going to stay around for quite awhile.

We are in phase 1 of our trip. We drove from Green Bay to Minneapolis yesterday. Our 07 Chev Duramax averaged 7-8 mpg towing our cat. Plenty of power. Just terrible mileage.
Well, our new ( older ) 06 chev duramax got 10mpg yesterday heading into a west wind and driving through the cities ( sitting in traffic for an hour ). I am much happier so far. We'll see how the rest of the trip goes.
I'm hoping now that we are out of Wisconsin, maybe other states have better fuel. Don't know.
WI fuel, I think comes from BP and is half salt water.

talala wrote:Maxtor,at 60mph my rpm is <1500>, if you order the camper pkg you get 3.55 rear end.

If you want a two wheel drive, you can not get the 3.55 gear ratio differential. We only use our truck to pull the WC, so do not need the 4x4 option. We ordered our current truck with 4x4 and camper package, but have not had a need for the 4x4. Being retired, we do not have to drive when the weather is bad. So for us, a two wheel drive is better, less money, less maintenance and better mpg. So if we buy a new Ford diesel truck today, it will not be with everything we want. So for now, until they give us more options, we will keep our 06 which is a very nice pickup.
The Ford 6.7 diesel makes great torque at low rpms, so the 3.55 gear ratio might work fine, but the 3.31 ratio at 60 mph would put it well below maximum torque rpm which is 1600 rpm unless you down shifted which would defeat the purpose for good mpg. Maybe later on Ford will give us more options.
For your needs, and for anyone who lives in a cold climate, it looks like you have a great pickup.