Mileage when towing...

J

JamesTXSD

Active member
When we were in Seattle for the boat show, the one diplay I kept coming back to, besides C-Dory (of course), was the GMC vehicles. That 2500 HD diesel looked mighty nice. We have been planning to tow our soon-to-be 25 Cruiser with our Leisure Travel Van (Dodge one-ton chassis). It has an 8400 pound towing capacity, and that concerned me.

Well, in our effort to consolidate our "stuff" for our upcoming boat travels, we got rid of our Tahoe and my hot Saab turbo convertible and bought a GMC Sierra diesel crew cab. 15,000 pound towing capacity, so there should be NO issue with the C-Dory. There's nothing in the manual about EPA mileage figures, so I was wondering if anyone here has any real world experience with fuel mileage with these? The salesman said to expect 20 mpg not towing, 16-17 mpg when towing. Realistic?

56 days 'till we are gainfully unemployed. For the first time in years, I didn't get out on the water during a calendar month (for April). All the posts here keep me going... thank you C-Brat friends.

Best wishes,
Jim B.
 
Jim,

I might kill for mileage like that.

We tow with a 2001 F150 Supercrew with 5.4 and the towing package and I added Supersprings, K&N air filter and Flowmaster dual exhaust. When bringing Valkyrie home from the Chesapeake after sea trials, we got 9 mpg, partly due to the mountains in PA.

Going to Lake Erie, with cruise on and overdrive off doing about 60 mph we're only getting 10-10.5. Without the boat we would get 16-18 at that speed.

Nick
"Valkyrie"
 
Jim: My "retirement sled of choice" was the 2005 Ford Excursion with the 6.0 turbo diesel. I love the way this thing tows. Fuel mileage, not talking about on the sales floor...but on real roads... goes sort of like this "in general...."
Towing TC24 loaded up as I used her which scaled out at about 7500 pounds.... "my vehicle" towed best on highways.... at about 2100 RPM, which runs about 72mph. Towing mileage ends up in the over all trip range which includes some city stuff for getting off...getting to where ya are really going... around 11.5 mpg. Towing a CD25 to a boat show with no motor.....I did not really have a chance to get her out on the highway as we were traveling Hwy 98 between Pensacola & East Point FL....which is about 50/50 of red light to red light....with a breather in there for the cities... I got about 13.5, but this boat was dry and had no motor....which could be tossed out because the trailer was not set up properly either and I had way too much tonge weight. My guess, set up properly and "wet" as we use them, highway would be about 14.5 to 16 with this boat, on the basically flat roads on the coast... Take off 1 mpg for moderate hills/elevation, and another one or 1.5 for big ol hills and real elevation.

I guess the bottom line on my vehicle is it is WAY comfortable, if I tow a grocery cart, I will give up 3 mpg from the highway average of around 18.5 to 19mpg. Then, it has NEVER been worse than 10mpg pulling the 7500 pounds of the TomCat. So....for figuring estimations of fuel use... I just use 16 for an overall....and by years end.... I will be close.

No chips, no pipes, or gadgets (yet)...32,000 miles on her now. So my guess is that if I would slow down to about 65mph....retirement speed... I could improve my fuel echonomy....but I ain't there. Check with Bill and El on Halcyon. Casey is also moving about reguarly and I know he too is a number cruncher.
 
Jim, I have a 2002 Chevy Duramax with the Allison transmission and get 16 to 17 MPG around town 19 MPG on the freeway and around 13 towing Shearwater. You did not say if you had manual or automatic, the manual will get a little better MPG. The only mods I have are a K&N intake system and Ispro boost and pyrometer gauges. I know the new models have a few more HP and footpounds of torque than my 02 but 16 to 17 towing sounds a bit optimistic.
Tows the boat like a charm

stevej
 
My guess is, the salesman is in the ballpark, but is probably being a little optimistic with the towing figure. The unloaded figure is close to what my Dad gets with his Duramax - he's got an extended cab, but I doubt there's a big enough weight difference compared to your crew cab to affect things much. When he loads up his truck with his heavy 12'6" cabover camper, he gets around 15.

Of the three diesels packages out there (PowerStoke, Cummins, Duramax), Duramax owners seem to report the best gas mileage, but not by much. Plenty of variables here, but my guess is you'll get around 15 on the flats when towing.

I get 15 with my standard cab 7.3 Powerstroke/4.10 rear, towing a 22 - a lighter package than you've got, but the Duramax is more efficient fuel-wise.
 
Jim B,

We had a 2003 duramax, allison with crew cab. The salesman quote on mileage for highway is right on. For towing alittle optomistic. On our 2003 trip from Wyoming to Alaska towing our 22 c-dory we averaged 14.7 mpg. We now have a 2006 duramax, 6 speed allison, crew cab, dually. Just wished we could do the same. GM sacrificed more power for mileage. On our recent trip to Lake Powel we averaged 12.8 mpg. The new truck does have a wonderful ride. On either one you would never know the boat was behind you. Got the dually due to planning on purchasing a fairly heavy truck camper and still towing the c-dory.

Jay
 
Jim B

One more thing. With our 03 going the 450 mile round trip to Yellowstone Lake we would average 17 mpg. That was due to the low average trip speed. Approximately 50 mph. As you know mileage is mostly determined by speed, weight and wind resistance.

Jay
 
Hunkydory":151ooj69 said:
Jim B,
<snip> we averaged 14.7 mpg. We now have a 2006 duramax, 6 speed allison, crew cab, dually. Just wished we could do the same. GM sacrificed more power for mileage.
Jay
Click to expand...

Jay, with some towing time since I last reported, your mileage is consistent with my 2001 Duramax/Allison towing the Jenny B. About 14.2-14.4 mpg. Towing a 27 ft. 5th wheel dropped it to no less than 11 mpg with occasional tail wind stretches hitting 13. I find that while towing the C-dory, mpg doesn't vary as much with speed and local wind direction.

I use the Edge Juice in level 2 while towing but it really makes no mpg difference.

Don
 
Thanks everyone for your responses. I am excited about how this truck will tow the C-Dory. Towing our Corsair trimaran with the Leisure Travel frequently gave us under 10mpg. When we towed with our motorcoaches (diesel pushers), it was like a freight train and the mileage didn't vary much, towing or not. Nice to have a diesel again. And really looking forward to towing the new boat to some gatherings! :D

Best wishes,
Jim B.
 
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