Gas vs Diesel RVs: 7 Important Truths About RV Fuels

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.

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

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.)

Like what you see in these videos? We'd appreciate it if you would Subscribe to our YouTube Channel (easy to do right here) and consider “ringing the bell icon” to be notified of any new video from us. 🙂 Thanks!

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-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

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!

---