Gas or Diesel Motorhome: Which is Better?

Which is better, a gas or diesel motorhome? That’s one of the biggest questions RV buyers need to answer. It’s important to ask and answer before buying a motorhome.

“Should I get a gas or diesel motorhome?” It’s a question that will repeat itself through the ages as long as we have fuel.

Maybe electric or another option will be added to the comparison charts in the future. In other countries, propane is a cheaper fuel. It’s used in many hybrid cars although it is rarely used in the U.S. and Canada  For now, it’s gas versus diesel.

RVers love to argue about the best RV fuel. Gas versus diesel motorhomes is the topic of many campfire circles. But we can’t argue until we understand the features and benefits of each type.

Let’s take a look.

A gas-powered motorhome © Rex Vogel, all rights reserved

Gasoline powered motorhomes

Gasoline is the most used fuel.  It is easily combustible which allows for quick starts and fast acceleration.  It is also the leading contributor to pollution. According to AAA, nearly 1/5 of all emissions come from vehicles. Your engine determines which grade of gasoline you can use. You have regular (87), premium (91), and mid-grade (89).

A diesel-powered motorhome © Rex Vogel, all rights reserved

Diesel powered motorhomes

Diesel is more fuel efficient. In traveling, you can usually go about 20 percent farther on a gallon of fuel than gas-powered vehicles. This is one reason why you will see most truckers with diesel engines. It also produces less carbon dioxide. But, it still creates nitrous oxide which causes smog.

There are six things to consider. I’ll go through them one by one.

A gas-powered motorhome © Rex Vogel, all rights reserved

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.

Without being overly technical, 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 mentioned above, a diesel engine is about 20 percent more thermally efficient than a gas engine. That means a 20 percent increase in fuel economy.

Diesel engines also run at a much slower RPM (revolutions per minute) than gas engines. 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 about RVing.

A diesel-powered motorhome © Rex Vogel, all rights reserved

2. Costs of gas vs diesel motorhomess

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 motorhomes are much more expensive than gas-powered motorhomes. For that reason, first-time motorhome buyers often decide to go with a less expensive gas-powered RV rather than a diesel or luxury unit.

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

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

A gas-powered motorhome © Rex Vogel, all rights reserved

3. Differences in mileage

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

Gas-powered motorhomes:

  • Depending on chassis, gas motorhomes will have between 80-100 gallon tanks (Class A) and 20-30 gallon tanks (Class B)
  • Average of 6-10 mpg (Class A), 10-14+ mpg (Class B and Class C)
  • Widespread availability at all fuel stations
  • Less expensive than diesel
  • Gas has an odor when burned; the smell can fill the cabin
  • Gas has a shorter shelf life due to evaporation

Diesel-powered motorhomes:

  • Depending on the chassis will have between 80-150 gallon tanks
  • Average of 6-18 miles per gallon with Class Cs and A motorhomes getting less, Class Bs and B+ RVs getting more
  • More expensive than gas
  • Diesel is available at most but not all stations but maneuverability presents a problem for most diesel pushers (Class A motorhomes)
  • Diesel has better fuel efficiency meaning less frequent refills at the pump
  • Diesel burns cleaner than gas
A diesel-powered motorhome © Rex Vogel, all rights reserved

4. Maintenance

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

A downside of a gas engine is that it runs at higher RPMs meaning 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 engines are considerably more expensive to maintain and require specialized training to service. Diesel engines run at a lower RPM meaning slower acceleration and lower top speeds but less strain on the engine and you can drive more miles between servicing.

A diesel-powered motorhome © Rex Vogel, all rights reserved

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 12,000-15,000 miles (depending on the chassis). You’ll need to change the oil in a gas engine every six months or less.

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.

A diesel-powered motorhome © Rex Vogel, all rights reserved

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? 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 Florida and Louisiana? In that case, a gas-powered engine would work well for you.

A gas-powered motorhome © Rex Vogel, all rights reserved

Gas or diesel: The bottom line

Simply put, the bottom line on gas or diesel comes down to your particular situation and preference.

YOU are the most important factor when it comes to the best RV fuel option. 

All the miles you drive, where you drive, how you manage your fuel usage, cost of ownership, how long you plan to keep your RV, resale value, and your RV maintenance habits affect you more in the long run. Hopefully, if you already own an RV, it meets your needs. 

We are RVers! We aren’t like everyone else already and neither does our fuel use have to be like everyone else’s. Whether we choose a motorhome that uses gasoline or one that uses diesel, the RV itself should match our travel needs. 

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.

Worth Pondering…

Get your motor runnin’
Head out on the highway
Lookin’ for adventure
And whatever comes our way
Yeah Darlin’ go make it happen
Take the world in a love embrace
Fire all of your guns at once
And explode into space.

Born To Be Free, words and music by Mars Bonfire