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Gas vs Diesel RVs: 7 Important Truths About RV Fuels

| Updated Jan 18, 2024

Which is better, gas vs diesel RVs? That's one of the biggest questions RV buyers need to answer…

It’s an important question to ask and answer before buying an RV.

There are 7 things to consider. Let's go through them one by one.

1. The Mechanical Basics

For those who might not know the difference between diesel and gas engines, it’s worth spending a little time talking about the basics. The Universal Technical Institute gives a thorough comparison of the engine types, but here are the key points.

The first and perhaps most notable difference is the thermal efficiency of diesel engines, which refers to the work that can be expected to be produced by the fuel put into the engine. As UTI reports, a diesel engine is about 20% more thermal efficient than a gas engine. That means a 20% increase in fuel economy.

Diesel engines also run at a much slower RPM (revolutions per minute) than gas engines (see image). Slower RPM translates to less wear and tear and a longer life cycle for the engine.

Gas vs Diesel RVs: 7 Important Truths About RV Fuels 1

Further, increased thermal efficiency also translates to more power and torque. A diesel engine’s high torque application is very beneficial for hauling heavy loads.

Gas engines, on the other hand, deliver a much higher volatility point but a lower flashpoint. A spark controls the combustion of a gas engine. Diesel engines do not use a spark, but what’s called a compression combustion engine.

Essentially, a gasoline engine is a spark-fired combustion, and a diesel engine utilizes compression.

Now that you have some background on the differences between gas and diesel engines, let’s look at the pros and cons of each with regard to RVing.

2. Costs of Gas vs Diesel RVs

Gas vs Diesel RVs: 7 Important Truths About RV Fuels 2

The first consideration for many people shopping for a new RV is the price. Simply put, does it fit your budget?

On the whole, diesel-powered RVs are much more expensive than gas-powered RVs. So, first-time RV buyers often decide to go with a less expensive gas-powered RV rather than a diesel or luxury unit.

But there are various degrees of quality within each type. Depending on what you are looking for, the best gas RVs on the market stack up against some lower-quality diesel units.

However, if well maintained, diesel engines have a longer life than gasoline ones and can still perform reliably after extensive mileage. This means diesel-powered RVs tend to retain their value longer and have higher resale values than gas-powered RVs.

3. Differences in Mileage

As mentioned above, the second factor to take into consideration is the gas mileage. After all, fuel is expensive and adds up over time. Here are the main differences of mileage between gas-powered vs diesel-powered RVs.

Gas-powered RVs:

  • Depending on chassis, will have between 80-120 gallon tanks (Class A) and 20-30 gallon tanks (Class B)
  • Average of 8-10 MPG (Class A), 10-14+ MPG (Class B and Class C)
  • Widespread availability at all gas stations
  • Cheaper than diesel
  • Has an odor when burned, the smell can fill the cabin
  • Has a shorter shelf life due to evaporation

Diesel-powered RVs:

  • Depending on the chassis will have between 80-120 gallon tanks
  • Average of 8-18 miles per gallon, with Class C's and A RVs getting less, Class Bs and B+ RVs getting more
  • More expensive than gas
  • Available at most but not all gas stations
  • Has better fuel efficiency, meaning less frequent refills at the gas pump
  • Diesel burns cleaner than gas

(By the way, be sure to check out my short video report on the best apps to find the cheapest gas in the video below.)

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4. Gas vs Diesel: Maintenance

Gas engines are much easier to maintain and repair compared with their diesel counterparts. If you have a general knowledge of gas engines, you can probably do a bulk of the repairs and maintenance yourself.

A downside of a gas engine is that it runs at higher RPMs. This means it will always be working harder than a diesel engine. Running at higher RPMs allows for a smoother, quieter ride with faster acceleration but more frequent upkeep is required.

Diesel RV engines are much more expensive to maintain and require specialized training to service. Diesel engines run at a lower RPM. This means slower acceleration and lower top speeds but there is less strain on the engine, and you can put in more miles between servicing.

A word of caution: To avoid a big maintenance bill, be sure not to accidentally put gasoline into a diesel tank, as one RVer once did.

5. Oil 

All engines require oil. Diesel-powered engines use a lot more oil than gas-powered engines, but the oil only needs to be replaced once a year or every 15,000 miles. You’ll need to change the oil in a gas engine every six months.

In a gas engine, if you know how to change oil, you can do it yourself. Diesel oil changes are more complicated, so you’ll probably have to take it to a professional mechanic to do the work.

6. Speed and Towing Ability of Gas vs Diesel RVs

Gas vs Diesel RVs: 7 Important Truths About RV Fuels 3

Gas-powered engines typically have higher horsepower and less torque, so you can accelerate and maintain higher speeds. However, having less torque adds more strain on the engine while towing and climbing inclines.

Diesel-powered engines are designed for higher torque at lower speeds but are not as fast as gas engines. More torque means slower acceleration speeds but greater towing power and ease in steep inclines.

As you can see, there are some pros and cons to both styles of engines, but ultimately, the decision for you boils down to personal preference and your budget.

Are you planning on carrying a “toad”? Do you frequent the Rockies and the Northwest mountains a lot? Having the power to climb hills with a load lends to diesel-powered engines.

Or are you planning on RVing without a “toad” and in relatively flatter areas such as New Mexico and Arizona? In that case, a gas-powered engine would work well for you.

7. Gas vs Diesel: The Bottom Line

Simply put, the bottom line on gas vs. diesel comes down to your particular situation and preference. We like diesel-powered RVs for their better fuel economy and higher resale values, but have also enjoyed our gas-powered RVs.

Every RVer's bottom line is different. If you don't plan to travel as many miles or aren't concerned about resale value, then a gas-powered RV might suffice for you.

Our RV Buying Secrets

Gas vs Diesel RVs: 7 Important Truths About RV Fuels 4

Next to your home, an RV is most likely the 2nd most expensive thing you'll ever purchase.

We get questions every day of other RVers wondering. “How do you buy a new or used RV?”

So we created a 75+-page downloadable digital guide to help you understand the nuances that come with purchasing an RV, where you can save thousands of dollars in the buying process, what the right questions are to ask dealers, what things to look out for, how to select the right unit, amenities, warranties, and so much more!

This ebook is designed to help make your purchase process as smooth as possible. And to teach you step-by-step exactly what to do so you can start your RV Lifestyle today!

Mike Wendland

Published on 2024-01-17

Mike Wendland is a multiple Emmy-award-winning Journalist, Podcaster, YouTuber, and Blogger, who has traveled with his wife, Jennifer, all over North America in an RV, sharing adventures and reviewing RV, Camping, Outdoor, Travel and Tech Gear for the past 12 years. They are leading industry experts in RV living and have written 18 travel books.

9 Responses to “Gas vs Diesel RVs: 7 Important Truths About RV Fuels”

October 20, 2020at9:26 am, Glen schlosser said:

I disagree about oil changes , I have a diesel and do my oil changes which is the same way I change the oil on my gas engine.


October 12, 2020at3:08 pm, Buying an RV: Seven Hidden Costs to Consider - RVing Outdoors said:

[…] Fuel is expensive. When looking to buy an RV, find out the average miles per gallon that vehicle has. Depending on if you’re going full-time or part-time, you can get a rough estimate of how much money you’ll spend on fuel in a month. Be sure to check out our post “Gas vs Diesel: Seven Important Truths About RV Fuels.” […]


October 12, 2020at7:25 am, Buying an RV: Seven Hidden Costs to Consider | RV Lifestyle said:

[…] Fuel is expensive. When looking to buy an RV, find out the average miles per gallon that vehicle has. Depending on if you’re going full-time or part-time, you can get a rough estimate of how much money you’ll spend on fuel in a month. Be sure to check out our post “Gas vs Diesel: Seven Important Truths About RV Fuels.” […]


October 08, 2020at10:18 am, Tyler Johnson said:

That’s good to know that a diesel engine will ultimately have less speed while towing, but more power. I like the idea of being able to tow a car behind me while I drive the RV, so that’s good to know. I’ll have to choose an RV with a diesel engine if I decide to get one for summer vacations.


September 29, 2020at11:36 pm, Seann said:

The one thing you failed to mention is gas is a solvent and diesel is a lubricant..


April 09, 2024at9:25 pm, danny beissel said:

Not with more and more epa trying to deal with low sulfur diesel removing more lubricant


September 29, 2020at8:49 am, Will Belden said:

Another concern, and I’m not sure this applies to diesel tow vehicles only or to diesel pusher RV’s, too, is that you may require DEF to go along with your diesel. We have an F350 and a fifth wheel. I *think* we have a 9 gallon DEF tank. It seems I rarely have to fill it, but using the TSD Logistics card to seek lower diesel prices, I often find myself at a truck stop. Those pumps typically have DEF. If not, you may find you’ll need to buy a box of it, and fill with the built-in spout. I also know that some tow vehicles have the DEF fill location under the hood. We are fortunate, ours is right next to the diesel fill cap. Only once have I had to buy a box of DEF. If you run out of DEF, you’ll find that your engine will run at a reduced ability or not at all, depending on the model and the level of DEF available for the engine.

(Note: DEF is a chemical composition that reduces diesel emissions.)

Also, I think you meant 80-100 gallons as opposed to 80-10.


October 14, 2020at2:56 pm, George Burkhart said:

I found your comments on gas versus diesel very informative but realize that had to cover a wide spectrum of sizes and types motorhomes. A area that your comparisons could have improved on was not considering MPG as the proper comparison between gas or diesel bur cost per mile. If gas is $2.35 per gallon and diesel $2.85 the diesel unit has to get considerably better mpg to make diesel pay. The other factor to consider is annual mileage the unit will be used to justify the up front costs of a diesel.As new to the rv ownership I really appreciate all the information your experience gives me to avoid mistakes you already know.


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