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Old 03-31-2014, 11:12 AM   #1
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Super C mpg question

I tried posting to an older thread but I was not allowed (Thread too old?).

I'm trying to decide what to "graduate" to (I'm currently pulling a 2010, 17' fiberglass Casita Spirit Deluxe Travel Trailer with a 23' 2010 Mercedes 3500 Sprinter). I'll be driving down to the Heavy Duty Truck Rally in Crossville, TN next week to get educated on HDTs & fifth wheel trailers. I've seen some nice Super C units and, have wondered what kind of real world fuel economy owners see. Is there much of a "hit" when you add an enclosed car / toy trailer? I understand the Dynamax units are among the best Super C models. Can anyone report on the Mercedes-Benz MBE4000- 450 12.8-liter 450-hp engine? Are there any advantages / disadvantages with pre-DEF diesels? Can anyone recommend forums on Super C units that I can study? TIA!
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Old 03-31-2014, 11:34 PM   #2
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Not much help for any forum ideas besides the truck based sections on here. Mine is slightly smaller than some of the bigger truck based class 8 chassis. Mine is a class 6 medium duty chassis. I get about 7-8 mpg with my Gulfstream Supernova, and that is with or without the open car trailer behind. The trailer just makes acceleration a bit slower, does not seem to affect mpg that much. A bigger trailer might have more effect, I think mine is in the dead air behind the motorhome, so it does not have much aero drag.

Pre-DEF saves you money and can be better mileage, but all the newer diesels have some mpg hit due to the emissions. Go back approx. 10 years for the best mpg before the real high level emissions hit. No matter what you will not get much for mpg, it is basic physics: weight and aerodynamics. Don't get a big truck and expect smaller vehicle mileage.

www.racingjunk.com is a good place to look for the big truck based motorhomes.
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Old 04-01-2014, 12:23 PM   #3
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I get 10-ish with our Super C (V-10 F550 chassis -30'11" length, 102" wide) when I'm being good (meaning driving the speed limit or lower, say 55-60mph). Unfortunately, unless I'm using cruise control, I often end up going 70+ and not realizing it as it rides that smooth (then I'm in the 8.5-ish range). Sorry, but can't tell you what I get when hauling our loaded race trailer (the empty trailer weighs about the same as a Jeep Wrangler, so when loaded with tools, fuel, gear and 5 bikes, it's considerably more) as it really isn't much of a concern. The point being, don't toss a gas powered rig out of your search. I'm a big diesel guy, but with diesel costing more per gallon, and diesel based rigs generally costing more than their gas counterparts (the 6.4 Powerstroke being an exception because of it's troubles), it may not pencil out to roll coal over a gasser. As Chev suggested above, aerodynamics play a huge roll. Our rig is very aero for a Super C. Dynaquest/max rigs tend to be very aerodynamic too (although they pale in quality when compared to our rig -Ha! Just a little teasing there). Blocky RVs with a large overhead bunk that protrudes way out past the cab roof is begging for poor mileage, in my opinion. Well, just my thoughts and others are likely to disagree. Good luck with your search!
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Old 04-01-2014, 12:33 PM   #4
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Quote:
Originally Posted by NY24 View Post
I tried posting to an older thread but I was not allowed (Thread too old?).

I'm trying to decide what to "graduate" to (I'm currently pulling a 2010, 17' fiberglass Casita Spirit Deluxe Travel Trailer with a 23' 2010 Mercedes 3500 Sprinter). I'll be driving down to the Heavy Duty Truck Rally in Crossville, TN next week to get educated on HDTs & fifth wheel trailers. I've seen some nice Super C units and, have wondered what kind of real world fuel economy owners see. Is there much of a "hit" when you add an enclosed car / toy trailer? I understand the Dynamax units are among the best Super C models. Can anyone report on the Mercedes-Benz MBE4000- 450 12.8-liter 450-hp engine? Are there any advantages / disadvantages with pre-DEF diesels? Can anyone recommend forums on Super C units that I can study? TIA!
We have a new 2014 Coachman Prism 24G on Mercedes Sprinter Chassis. We have two slides and we have been averaging 15-1/2 MPG on our fill-ups. We were told that as the engine gets broken in 10,000+ miles then we will see better mileage. We are already happy. We had a 2013 Pleasure-Way Plateau on the 3500' on the Mercedes chassis and we were getting around 18 on that, so with the extra weight of the Coachman with the slides we are very happy with the mileage, although we don't pull a trailer or a car so we may not be any help at all.
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Old 04-02-2014, 08:27 AM   #5
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I misspoke above. The worst I ever got was 8.5, but that was in an extreme situation (insane headwind across WY in Winter (empty semis advised to stay off road)). 9.5-ish when heavier on the throttle than I should be (or lots of steep passes).
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Old 04-06-2014, 12:03 AM   #6
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Avg 7.8 mpg after 15,000 miles and lots of hills, Cummins ISC 350 Dynamax 34XV
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Old 04-07-2014, 06:22 AM   #7
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Avg 7.8 mpg after 15,000 miles and lots of hills, Cummins ISC 350 Dynamax 34XV
Wow- someone who posts real fuel mileage. I have the same engine and that is exactly what I got on my last 2,400 mile trip I checked. Every place else I read guys pretending they are getting 10+. Does yours have the dual 50 gallon tanks?

To the OP- I know several guys with that MB 450 in Columbia chassis motorhomes. They get around 7. A little less pulling stackers.
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