Fuel mileage with Cummins ISL

[dougburi]

To all the folks with lots of experience (and miles) out there driving a late model year 40 foot more or less DP with a Cummins ISL -- What is your average mpg over say a 1000 miles or more?

[RVThere]

Over the last 30 fill ups, we average 6.3 MPG. www.fuelly.com gives you great tools for easily tracking mileage and even works from your web-enabled cell phone. Here are some recent MPGs from last fall.
Ranges from 5.5 to almost 7

[DonnaB]

2007 Dutch Star pulling a 4 door jeep, about 4800 lbs. DSDP is right at 34000 lbs. Over 40K miles on the coach. Now running around 7.5 MPG. Primary driver works real hard to keep the MPG as high as possible. Uses Silver Leaf to run at optimum.

[d.polka]

2004 DSDP 4010 pulling 4 door Jeep Commander LTD and a full basement of "stuff". Just turned 60 K and at 1800 RPM (62 MPH) I get 8 MPG or better, depending on wind. Started at under 7 MPG new and has been getting better with mileage. Was told that the mileage will get better once the unit gets over 40,000 miles by truck drivers. And it has prove to be true. But another part of the story, I have slowed down since I retired. Use to drive 5 to 10 MPH over the speed limit, except in towns.

Spartan Mountain Master chassis
Cummins 370 ISL
EMS-LCHW50
Pressure Pro
WaterStick

Dale, Mama Lou, and Brandy (our pom)

[Norm4015]

I have a 2005 Dutch Star 4015 that weighs over 31,000 pounds and I tow a 3,600 pound Honda CR-V. The first 10K miles it averaged 7.8 mpg and then next 10K miles it averaged 8.5 mph. About that point I guess the engine got broken in and the last 10K miles it has averaged 9.3 mpg. During that span the lowest tank was 8.8 mph and the highest was 9.9 mpg.

I have a VMSpc Silverleaf Monitor and it shows a higher fuel mileage than I actually get. All of the above numbers are using a pencil and paper to figure the mileage.

[GaryKD]

Hi dougburi,
My ISC, pulling an 05 KSDP at 37K total lbs, runing 60 MPH on Interstates and the speed limit in secondary roads, 58K miles got 8.3 MPG before the after treatment device was installed on the exhaust. It now gets 7.5 MPG. These are manual fuel calculations, no computer calculations.

[Dav5942]

42ft '07 Allstar, 50,000 miles, 32,500lbs. 7.5 MPG(actual calculation no computer guessing) overall average with toad and toys(Harley, 2-ATVS, etc.) in the garage. Mileage has NOT gotten better with age, actually slightly less as it is an Old Wives Tale of imporoved mileage with a diesel.

[Brigadoon]

I also have a '05 Dutch Star 4015 (44,000 miles) pulling a Jeep Wrangler, total weight 34,750. We started out in the high 7's and over time we worked up to a 8.2 mpg average at 62 mph. Like the others, I fill the tank carefully and calculate manually.

[dougburi]

Thank you to everyone who replied. It looks as if the Cummins ISL averages close to 8 mpg. Does the "computer" agree with actual fuel use?

[Dav5942]

Quote:

Originally Posted by dougburi Thank you to everyone who replied. It looks as if the Cummins ISL averages close to 8 mpg. Does the "computer" agree with actual fuel use?

Yup, overall pretty close, but NOT on a daily/tankful basis!

[Darrel]

My 2007 KSDP has returned 6.28 MPG for 11,600 miles. My ISL is an oddball however since it is the 350HP version. I pull a 4000 lb Jeep grand Cherokee and mostly move at around 62MPH.
The idea that mileage will improve was also explained to me. I have not seen any improvement yet though.

Have a nice day - Darrel

[JVR]

I had an 2002 American Eagle prior to the Essex 4508 that I presently own, The Eagle had the 370hp version and the fuel mileage was great, always in the 8 range, averaging about 8.5 with a max of 9.3, not towing. The significance of my figures is that I don't try to drive economically and I can only wish the Essex could come close, it's never seen 7mpg, but I am very happy.

[rcatter]

Our unit is new to us. 2003 DS with 350isc. We have been on two weekend trips so far. This weekend we traveled 750 miles round trip pulling a 4000 lb trailer and carrying full load of water for boondock weekend. Checked mpg and it was 7.08 by manual calculations. Not pretty numbers with diesel over 4 bucks a gallon. Also want to add we were set at 68mph on cruise control. For this rig that seems to be the sweet spot on the interstate from a handling perspective.

[Brigadoon]

You might do a little better at 60-62 mph. If you are short on time, you're trading fuel mileage to make up time. If possible, light on the trottle pays dividends. But if you need to make time...power up!