Mileage

[FarmLife]

We have a 2000 Monaco Diplomat 38’ with a 315hp Cummins with a turbo with a 6 speed Allison transmission with eco mode.
We are getting ready to do some traveling and wondering how flat towing or a car hauler trailer affects the mileage.
I know driving techniques affect it but if I drive the same way.
Thank You

[ChrisDParise]

Though not a diesel, instead a Class C with the V10 and 5 speed with tow/haul and the Ultra tune from UPFORD, I get better gas mileage towing. 7.2 vs 6.8 mpg. Flat towing a 5000+ lb GMC Acadia.

My reason for better gas mileage towing vs not towing is my toad is limited to 65 mph and I usually have the cruise set to 63-64. When not towing, I'll set the cruise to the posted limit. Higher speeds at least on gassers results in lower fuel economy

[Dutch Star Don]

As a generic guess across all driving habits, engines and weight of toad, you'll probably see a 1 mpg lost.

[d23haynes57]

For my Cat C7 powered 39' Tropi-Cal towing a VW Vanagon Camper it was about a 1 mpg loss. 7 to 7.5 vs. 8 to 8.5 mpg.

[wildtoad]

In general, as above, towing a car will reduce MPG in the 1-1.5 mpg range. The more weight, the more tire rolling resistance, and higher MPH will adversely affect that number.

[fcb1313]

My RV is a 2023 Jayco Redhawk with the 7.3 Godzilla Engine. I get approx 12 mpg without a toad and 8.6mpg with the toad. My toad is a 2020 Jeep JLU.

[crb478]

For me with a 25000 lb coach 3126 cat 330 hp and usually staying 65 or less I have gone from a high of 11 mpg usually 10, to towing a 2013 CRV and getting between 9 and 8.3 MPG. It so far has never gotten less than 8.3 so I always figure 8 mpg for my fill ups. Wind and hills make the biggest differences.

[Gary RVRoamer]

As you can see, the numbers are all over the map. I think for a diesel pusher, some where between 0.5 & 1.0 would be typical.


Assuming the driving habits and speeds are the same when towing, I think the toad weight relative to the coach is the key factor. If you have a 22,000 lb coach and add a 4000 lb toad, you've increased the load by about 18%, a fairly big hit. Diesel pushers are typically much heavier than gas coaches, often 30,000-35,000 lbs for 34-40 footers. That same 4000 lb toad is only an additional 12.5% for a 32,000 lb DP, so the impact on the mpg is relatively less. If you are driving a big rig, it's literally true to say "hardly know it's there".

[MRUSA14]

Originally Posted by Gary RVRoamer

As you can see, the numbers are all over the map. I think for a diesel pusher, some where between 0.5 & 1.0 would be typical.


Assuming the driving habits and speeds are the same when towing, I think the toad weight relative to the coach is the key factor. If you have a 22,000 lb coach and add a 4000 lb toad, you've increased the load by about 18%, a fairly big hit. Diesel pushers are typically much heavier than gas coaches, often 30,000-35,000 lbs for 34-40 footers. That same 4000 lb toad is only an additional 12.5% for a 32,000 lb DP, so the impact on the mpg is relatively less. If you are driving a big rig, it's literally true to say "hardly know it's there".

I second what Gary said. Driving a DP, there’s hardly any difference towing or not towing. The biggest difference in towing cost will be at the toll booth.

[d23haynes57]

Originally Posted by Gary RVRoamer

As you can see, the numbers are all over the map. I think for a diesel pusher, some where between 0.5 & 1.0 would be typical.


Assuming the driving habits and speeds are the same when towing, I think the toad weight relative to the coach is the key factor. If you have a 22,000 lb coach and add a 4000 lb toad, you've increased the load by about 18%, a fairly big hit. Diesel pushers are typically much heavier than gas coaches, often 30,000-35,000 lbs for 34-40 footers. That same 4000 lb toad is only an additional 12.5% for a 32,000 lb DP, so the impact on the mpg is relatively less. If you are driving a big rig, it's literally true to say "hardly know it's there".

I think the big driver for fuel economy being affected by towing is the increased wind resistance. The air that drops down behind the motorhome and then need to have the towed vehicle pulled through that turbulent mess.

[Old Scout]

Yup--what Gary said--"your actual mileage will vary." Wind direction and speed, mountains, and your right foot will have more impact on MPG than the towed. The "Eco" mode on the Allison will make little or no difference on MPG--my experience.

[d23haynes57]

When I had the 04 Tropi-Cal with the C7 the ECO mode made a definite difference in the shift points as long as I had a light foot. Worked really well in traffic to keep the revs down. Hit the pedal to go and no difference. Also, once the cruise control was active ECO mode was disabled. For the rig I have now I can't tell any difference mode light on or off. I don't even know if it works. Gearing and shift points are just so different though. Still learning what is normal.