Home RV Shopping The Eternal Fuel Type Conundrum: Gas vs. Diesel

The Eternal Fuel Type Conundrum: Gas vs. Diesel

by John

Thanks for following along in our saga of finding our new RV, and whatever adventures that brings. One of the first decisions we had to make was Diesel or Gas? We (well, me, primarily) chose Diesel.  I remain convinceable, and really am open minded about the idea, but I’m definitely on the Diesel side of the fence at the moment.

 This is only our second RV.  But, we’ve spent an awful lot of time inculcating ourselves in the RV universe.  Lots of reading, video watching, and talking to other RVers.

I have noticed some important things. There are a lot of very nice (Prevost/Newmar/Tiffen/etc) coaches, and all of their mid-to-high end offerings are diesel. So, that got me thinking. (It got the Wynns thinking too – they have an awesome, and informative video series about Gas vs Diesel here) They greatly informed our decision. Interestingly, they are also currently (2015/16) in a Gas Coach, which they seem mostly happy with, after some modifications. (Seriously, see their videos and blog entries, herehere and here too)



Much Cheaper

I could conceivably do some minor work on it.

Abundant filling stations

Cheaper Fuel


Limits the length of the coach a little. The longest gas coach I could find is well within our expected range (33-39′) at 36′, however. There aren’t many, and they all use the (respected) Ford Triton 6.8L V10 engine on the F53/F550 [?] Chassis.

Power – I don’t think we’re going to be racing around near-vertical mountains or anything, but there’s something disconcerting hearing that gigantic V10 roaring when you’re just going up a little bridge. High altitude performance is lower as well.

Mileage – for our size range of coach, we will expect to be in the 6-8 MPG range.

Manufacturer limitations – choosing Gas as a requirement eliminates a good chunk of the nicer coaches offered by manufacturers. Some (Tiffen/Newmar) make really nice gas coaches, but they’re still on the lower end of the manufacturer’s spectrum.

 Anecdotaly, I’ve noticed that in YouTube videos, the gas coaches generally seem to be more rattle-y and otherwise noisy.  But, most RV-centric Youtuber’s videos don’t have diesels featured, making comparisons difficult.  Also, actually being in the RV is going to be a far better determining factor, rather than attempting to compare ambient and other noise across different YouTube videos.  People encode and filter differently, have different cameras, and have their rigs set up differently.



 Everything is more expensive – fuel, maintenance, upfront cost, etc. This also translates into more residual value too, however.  (Particularly if maintained well)

 I will probably only be able to do the most trivial work on this engine. Changing filters, checking obvious connections, etc.


Diesels are what power most of the coaches in manufacturer’s offerings, or so it seems. This opens up a lot of possibilities for us.

Increased MPG – as I understand it, if we were to compare the same coach with a diesel and a gasoline engine, we’d see more MPG from the diesel. Some part of this is that the diesel generates a bunch of Torque, which is more useful to big trucks and RVs, but a bit of it is the increased energy density of the fuel. Diesel can cost more, but packs more energy in the same volume.

Quieter – in a diesel pusher, the engine is in the back, rather than under your feet. It also should be working less hard.

Diesel-y things – pneumatic brakes (they engage if the lines get cut, rather than being unusable if the lines get cut) – Freightliner chassis and air-ride suspension, very low emissions (thanks DEF) putting it in the same ballpark as modern gas engines – or so I currently think. Expected lifetime should also be higher.  Diesel generator in the front – away from the Bed (for those times that we use it).  Better designed transmission – or, better shift points and smarter cruise control and # of gears.

[Neither] Diesel is also a separate market from Gasoline, so when gas prices goes up or down, diesel doesn’t necessarily follow.

Of these, the factors that seem to ring the most true with me are: the wider selection, the quiet, and the ride of the Diesels. We have a gasser now (a stumpy Forrest River FR3 28DS named Boomer) which is absolutely perfect for the weekend/occasional week trips we take in it.  It’d probably be ok for even longer trips.  But, I think a diesel is going to be a basic requirement for us.  Probably Cummins on a Freightliner chassis with an Allison transmission. (The extreme majority are exactly this, just varying sizes or models of each)

Its also worth acknowledging that other, far more experienced RVers do very long trips in their Gassers as well – like His and Hers Alaska (http://his-hers-alaska.com/).

So, we’re primarily focusing on diesel coaches, for the reasons above.  This narrows down the search space considerably.  In future posts, I’ll talk about some of the other ‘must haves’ we’re considering.  (like an RV fridge over a residential, etc)

What do you think?  Did we get it wrong, or are the other considerations we’re missing?

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Dahkota February 15, 2016 - 12:38 pm

We had the same choice to make two years ago. Mike wasn’t going to buy anything but diesel. However, there were only two diesels available less than 35′. And, understanding how we camped and where we camped, length became the determining factor. We had multiple choices at that size in gas and we liked the layouts better. So, we ditched the diesel plan. We saved about $35K, kept our coach small enough to get into our favorite campgrounds, and have been happily fulltiming ever since. We drive ten hours a week and park the other 160+ most of the time. Where we park and the livability of the layout is far more important than how quiet it is when we drive.
If you are checking out diesel coaches, have the salesperson turn the generator on while you are relaxing in the living room (even with 600W of solar, we still have to run the generator occasionally). That little test killed the sale of one diesel coach and pushed us towards gas.
Best of luck in your search! It took us six months to find ours. But even a year and a half later, we are still convinced it is the best rig for us. Except for the carpet. We really want to get rid of all this carpet.

John February 15, 2016 - 10:26 pm

Hey Dahkota!

The length requirement is less hard-and-fast for us. I would prefer shorter – if only to open up some state parks closed to larger rigs – but its not a showstopper.

And I totally agree – I think the main criteria should be the floorplan. That’s about the only *real* differentiator right now. We have some themes we like – L-Shaped couch, free-standing dinette, room for me to work, etc. – but only a few have all that we really like. The length just gives us more options to choose from, as does diesel. However, your point about driving 1/16th of the week is well taken, we’ll have to noodle over that a bit.

I think, for the sake of accuracy, what I really like is the Freightliner Chassis. Air Ride suspension/Air leveling etc really are nice, and very noticeable when we were poking through the RVs at the show.

I hadn’t thought about the generator’s location too much. Just that it was farther away from the bed. Our current rig has it right under the dinette. The rumble is noticeable, but not overwhelming. I’ll definitely get the future salesman to crank it up on whichever we start looking more seriously at. I”d like to not run it at _all_. I have a post about solar with a residential fridge, where I (well, I think i do) work out that its possible, just a little more challenging.

And, yes – ixnay on the arpetcay!


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