[PNW_Steve]

Hey Everyone,

I have been lurking here for some time and enjoyed the community. I finally decided to jump in after completing a 5000 mile road trip in my 2001 Dodge Ram 3500 4x4 Diesel truck hauling a 27' 5th wheel trailer.

I managed a trip average of just over 12.9mpg. My best tank was 13.2mpg.

I managed to do a pretty good job of maintaining my "self imposed" 60mph speed limit. The onboard mpg display is not terribly accurate but it will demonstrate deltas in mpg and shows a significant drop in mpg over 60mph.

My previous RV was a converted Eagle 10 bus with an 8v71NA Detroit Diesel and an Allison 740 transmission. I got a consistent 7.25mpg with that rig. That started when diesel prices were well under $1.00 a gallon. As fuel prices increased and my ability to afford fuel diminished I finally gave in and sold my trusty bus.

Here I am again trying to balance my love of travel with the cost of fuel.

On my recent trip I spent a great deal of time talking to other RVers about fuel mileage, driving habits, rig and accommodation details. I have come to the conclusion that as much as I enjoy a 40' rig that will cruise comfortably at 70mph I don't NEED it.

Our 27' 5th wheel was very comfortable for 5 weeks on the road and certainly much more economical..... What can I say... I want more! (MPG).

I have been searching for a solution that I can afford and see that the new breed of eco minded factory RVs are way beyond my budget. That got me contemplating a build.

I am contemplating a 12V Cummins based platform. Either a Ram 3500 truck or a B350 van. Some sort of "hybrid" Class B/C. Basically take the Dodge cab & chassis and build an aero "box" around 20' long & 8' wide for the "house". Features to include:

12V Cummins Diesel with minor mods aimed at economy.
5 or 6 speed manual transmission.
2 speed rear end or Gear Vendors overdrive.
Tire selection to maximize economy.
Full fairings on the "Box"
Ground effects: Air dam & side skirts as appropriate.
Smooth wheel covers.
Partial wheel skirts.
Airbag suspension that will allow me to lower the rig when needed.
General "smoothing" of the exterior as I am able.

Picture one of the newer "AeroCab" semi's with a smooth box on the back. Some kind of ducktail included.

Has anyone out there tried something of this sort? Results?

I am really hoping to see something that is really livable and can accomplish 20+ mpg highway. Being able to run 65mph and still get 20+mpg would be a bonus.

Any tips on the aerodynamics would be quite helpful.

Thanks

Steve