Why don't we see more fuel-efficient RVs?

Why don't we see more fuel-efficient RVs?

While we're waiting - "the most significant variable is the driver"...

Roadtrek RS model - "up to 22 mpg @ 65 mph" - do you know a more fuel efficient RV? - add your comments below...

This is a question asked over and over by Roaming Times readers - "why don't we see more fuel-efficient RVs?"

Maybe you have your opinions - add them at the bottom of the page...

The real alternatives RV manufacturers are looking at include the following:

Reduce vehicle weight. This requires the use of lighter materials and a rethink on the design of the RV structure
More efficient engines. Engine manufacturers are of course looking closely at this. For example, in July of this year, the US Department of Energy extended their partnership with Volvo to develop trucks with greater fuel efficiency. $48 million is being invested to test and analyze biofuel use and hybrid vehicle technology.

So it looks as if we need to wait for a truly more fuel-efficient RV. In the meanwhile, what can we do? The following is quoted from Caterpillar's "Understanding RV performance":

"The most significant variable affecting fuel economy is the driver. The driver controls the vehicle speed, acceleration rate, brake usage (service, compression, or exhaust), cruise control usage, automatic transmission shifting override and “mode” selection, tire inflation pressure, and more. It is not uncommon, for identically spec’ed coaches to experience as much as a 20% (6.0 vs. 7.5 MPG) difference in fuel consumption between the best and the worst drivers."

We keep on waiting for more fuel-efficient RVs, but in the meanwhile "The most significant variable affecting fuel economy is the driver"

What do you think? Read RoTi readers' comments below and add your own opinion ...

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READERS' COMMENTS

(Latest comments first)

What do you think? - add your comments here

author	comments
Norris	When you generate electricity charge a battery and run an electric motor you lose at least 30% of your power.
TGA	Powering a smaller size RV with say 4 diesel generators run in parallel under electronic load control should provide enough power for electric motor (or motors) propulsion. Probably would still need some battery capacity for high-current demands like freeway ramp acceleration. However, every aspect of the vehicle would have to be optimized (weight, aerodynamics, tires/wheels, etc.). Unfortunately this type of innovation doesn't seem to be important to buyers because they keep buying the same old technology year after year.
nich	This is realy a very stupid idea . Lacks imagination ,practicallity & engineering . I get 14-16 miles out of my diesel now .Seems to me this could be much better with the newer diesels on the market .I have seen to many hair brained schemes over the years & this is one of them .
jeffbec51	I've owned 7 RV's from the diesel pusher down to 27' Class C Ford 450 (gas). By going smaller, we improved efficiency by almost double. We NEVER towed a vehicle; the 27 doesn't need a toad. I think your idea of the cab uncoupling from the living accommodations is terrific. Cures the toad problem! I look forward to efficiency improvements, but smaller is the way to go for now.
Eli Maz	There is actually new hi-efficiency engine inventions out there in the hands of some independent inventors that have no mean to bring thier ideas to the market because of lots difficulty in finding either investors or regular engine manufacturers that are not willing to admit to the fact that there is a better ideas (inventions) in the hands of somone else other than their own company and they are no willing to think outside the box, I know a close friend (MasterMechanic/Engineer/inventor) of mine that has a very new and revolutionary idea on how to redesign the internal combustion engine from the ground up, the total redesign is already done in 3D CAD and is very simple to manufacture. Yet not takers. The only companies that have contacted him are from china and he refuses to outsource this American idea to the chinese, enough jobs are going overseas. Yes there is a much better technology, no there is no one out there yet, I hope someone from the States will contact my friend soon to make this new engine a reality. Imagine a regular RV the is normaly 6-10 mpg will more than double with this new engine, that good.
israndy	The Prius works because as a daily commuter you are stuck in stop and go. Thus recapturing the energy helps with milage. Most RVs are just b-lining to the next location and thus are mostly fighting wind resistance. The Vixen had fiberglass body that was smooth all around and only 6' tall. Combined with an efficient Turbo Diesel it got great MPG. Currently the Sprinter based RVs have pretty smooth exteriors and Turbo Diesels, but still only get 22 MPG or less due to modern emissions controls. Using a Diesel Generator works for trains as they let the engine run at most optimum RPM and turn the electricity into fuel for the motors. But they have as long as it takes to speed up. To get up to freeway traffic speed you need more pickup. Solar is a great addition to power the refrigerator and the lights, but a day of charging batteries would all disappear getting up the hill onto the freeway, it's just that much energy to move an RV. If you take the most fuel efficient design, Turbo Diesel, and try to Hybrid it, you loose the power of the Turbo. Turbo gets it's power from a spinning turbine, but the hybrid gets it's savings from stopping all moving parts. So now you have to drop back to just a diesel or gas engine to get they hybrid working, but you won't get enough savings, except for stop and go traffic, to make it advantageous to have lost the Turbo. My wife works for the local bus company, check out the technology they are using to get those vehicles up to speed, and they are stuck in traffic.
Colin H	There's some good ideas here but it would take a lot of research money and the rv manufacturers have had a tough time lately. Needs government support money?
David W	The best arrangement using current affordable technology would be the type we see on a Prius, except with a diesel instead of a gasoline engine. The engine can run when necessary to push the vehicle through a mechanical transmission and/or charge the batteries through a motor/generator, the motor/generator can push the vehicle when necessary, and the batteries are available for powering the motor/generator and/or anything else within the RV. This hybrid arrangement can increase fuel mileage significantly (not just from 10 to 12 mpg or 15 to 18). One of the best things about it is that the necessarily large capacity batteries can power the RV while parked much longer before needing charging. The same engine that pushes the vehicle can be used to recharge them. Since they're quick-charging (have to be in order to have regenerative braking), the engine would not run long and hence not suck up much more fuel than a dedicated generator. The downside is the cost of the batteries, though with a vehicle as heavy as an RV, they needn't be the most expensive Li-ion type but could be NiMH or something else less costly. Having enough capacity with lead-acid or NiCd would add too much mass and bulk. The shape, regardless of size, will need to be something similar to a current Sprinter-based or old GMC RV for drag-reduction. Low rolling resistance tires are necessary, and towing another car will hurt the mileage, due to its tires' rolling resistance, mass, and additional air drag. Anytime the RV has shore power, the batteries can be topped up, so that the RV can run that much more efficiently when moved again. Increased use of the type of materials used in airliners would help with the vehicle's mass. We'll have to give up real wood cabinets, tile floors, and Corian countertops. A good area for R&D is creating a dockable RV, where the "cab" can be undocked to drive around separately. Perhaps it has the diesel engine and front wheel mechanical drive while the electrics are built into the back end and stay with the parked part. The diesel is only 120-150hp because the electric motor does a lot of the work (hill-climbing, accelerating, etc.) while the pieces are docked, so the undocked cab's mileage isn't too bad. The real R&D work is making a good docking system where the parts act as one while docked and ensuring that the handling of the whole RV and the cab along are both good.
Al T.	I have been searching for a fuel efficient RV for years. The only thing I found is the Vixen TD. Made from 1986-89. They were way ahead of their time and the diesel model got 30 mpg !!! Also, If you talk to 18 wheeler drivers, those big rigs get 6-7 mpg and their moving 50-60,000 lbs or more! Why does a 20,000lb motorhome get only 7-8mpg? Bad designs? Wind resistance? Or is it gearing?
Richard A	Greater fuel efficiency on a truck diesel/electric chassis has been running around our cities for some time..in the form of diesel electric buses....thank you for FINALLY doing something with RV's
William K	We downsized from a 40' motorcoach to a class B and the fuel consumption is better of course. But engine builders and RV manufacturers still have a long way to go. We need more fuel efficient vehicles, where's the hybrid designs for RVs?
Ross Kelly	There's no commitment by RV manufacturers to building different RVs. Until an engine builder provides a better engine at a cheaper price nothing will change.
Walt R.	I'm thinking about purchasing a 29 ft. Puma Travel Trailer. Any feedback as far as reliability, any major repairs, trouble with service request or quality of product?
Christopher Beale	I don't think the RV manufacturers will spend money on research during a recession. The research will come from engine and chassis manufacturers and I don't think they're doing enough.
Kenny P	Motorhomes will change but it will take a few years. I can't really see any new ideas. Maybe you can make an electric car but a truck engine? I don't think so.
Nomad66	I would like to see a diesel electric motorhome... instead of a diesel genset and a diesel drive motor, why not one small to midsize engine driving a genset, with a large battery pack, regenerative braking, and a large set of solar panels on the roof? The extra weight of the batteries could be offset by the smaller diesel engine.. Toyota prius has proven that it is viable for a car, why not a motorhome?
Paul J	I've looked at the websites of the big diesel engine makers and I don't see any indication that they're spending big money on research and development of new engine types. Truck engines are big business and a big source of polution. I read about Volvo trucks and the government money but this is all small change really. Where is all the real money going for research into truck engines? Or is it happening in China or Japan?
Tiretramp	Surly you jest. driving a 30 ton MH towing a toad and even hauling the Kitchen sink with you and you want better fuel efficiency. Want better fuel efficiency, go smaller, simple cure.
Lenich	I have been motorhoming for over 55 years now and have never seen a change in ANYTHING.Motorhome MFG's are the worst as they have no inspection .If any changes come it will come from the automotive & engine mfg's mainly.New ideas are expensive & mfg's have very few enginers that motorhome for a vacation.If your not a millionare you can't even afford one today.
John A	It takes a lot of money for research and development and the RV manufacturers generally don't have this money especially with sales like now. The money for engine improvement work needs to come from engine builders or some new company with a new idea. Chassis manufacturers will take up the ideas, incorporate them and pass them on to the RV manufacturer.
JT	Look at the new Coachmen Freelander on the Sprinter Chassis, it's in the 60s and yes they do get great fuel mileage
Mr. Frustrated!	Mini to large motorhomes have on-board generators. So with all of the hybrid technology why can't can't motorhomes go hybrid since the power source is already installed. Note with the large roof area could also have solar to recharge the batteries with a small wind generator you see on some sailboats to add "free" energy. In addition, they are using the large diesel engines on ships to power generators used to power the electric propellar pods!
Ross TX	There seems to be more and more research funding into biofuel and engine efficiency. I hope it means engines will burn less fuel more cleanly and it'll cost less.
Slyckstar	Fuel and energy efficiency is the are the areas that will see major improvements. Both diesels and gasoline engines will become more fuel efficient along with lighter and stronger materials being used in construction.