Which is better – a diesel RV or a gas RV? There is no simple answer to this question, though if you spend any time in online RV forums you’re sure to find people who feel that there is. The reality is that neither is clearly the best choice for all RVers in all circumstances.
The best choice for you depends on a wide variety of factors. Consider all of these factors before deciding if you want a motorhome with a diesel or gas engine. If you’re wondering why the type of fuel should even be a factor, read on to be sure you make an educated choice. Then, take our quiz to help you determine which type of RV is most likely to suit your needs!
This explanation is focused on Class A, B, and C motorhomes since these drivable RVs are the ones with engines. Most of these factors are similar, however, when choosing a tow vehicle for a fifth wheel or travel trailer. Specific considerations for vehicles pulling towable RVs will be discussed at the end.
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Determine Your Needs
Before you’re ready to decide which type of engine will best suit your needs, you should clarify what your needs actually are.
What are your plans for your RV? Will you live in it full-time or use it mostly for weekends and vacations? Are you planning to travel far and wide or stick to a specific local area? Will you be spending a lot of time in the mountains or up at high altitudes? Do you plan to tow a vehicle behind your RV to use for errands and sight-seeing? How many people should your rig comfortably accommodate? Are you comfortable driving a large, heavy vehicle or would you prefer something smaller?
Your answers to these questions will help you determine your travel style and which class and size RV is best for you. You should also consider if you are shopping for a new RV or hoping to find a used one. There are many advantages to getting a used rig, but some types of engines may be hard to find in certain classes of RVs on the used market.
When discussing the different types of RVs, it is helpful to remember what the three classes of motorhomes refer to:
Class A: Class As are the bus-style motorhomes. They can range from about 29-45 feet long.
Class B: Class B motorhomes are van-style campers. These are typically about 17-23 feet long.
Class C: Class Cs can be easily recognized by their distinctive fronts with a bed or storage space over the cab. These come in a wide range of lengths.
Gas vs. Diesel Motorhomes
The factors you should consider when choosing between a gas or a diesel engine on your motorhome can be broken down into three important factors: financial considerations, performance considerations, and matters of convenience.
Initial Purchase Price
Diesel rigs are generally more expensive to purchase than their gas-driven counterparts. This is true for both new and used models. If your purchasing budget is tight, you’ll find RVs with gas engines to be more affordable.
Simply comparing the price per gallon of fuel, diesel fuel is more expensive than gas at the pump. Diesel owners should also factor in the cost of keeping their diesel exhaust fuel (DEF) tank full as well. DEF can be purchased by the gallon, similarly to fuel. The rate of DEF consumption varies per vehicle, but you can estimate 2-3 gallons of DEF for every 100 gallons of diesel.
If all other factors are the same, diesel fuel gets more miles to the gallon than gas. There are many factors that can affect the fuel economy of a vehicle, but if you compare well-maintained engines of the same size, diesel will take you further on each gallon. According to a resource from the U.S. Department of Energy, the difference can be as much as 20-35%, which may often compensate for the price difference at the pump.
One thing that makes this difficult to estimate is counting on a “fluid economy” on diesel RV engines, not just fuel economy. Fluid economy takes into account how much DEF the vehicle consumes. Better fuel economy means you don’t need to stop for fuel as often, which could also save you money on impulse purchases at the gas station.
Maintenance and Repair Costs
Maintaining and repairing a diesel engine generally costs more than a gas engine. Diesel requires more oil than gas, so getting diesel oil changes costs more. Diesels also use more filters and other parts that need to be replaced regularly as a part of standard maintenance.
One advantage of diesel engines is that they don’t use spark plugs or distributors, which account for many tune-ups and repairs on a gas engine. When it comes to repairs, though, both the parts and the labor for a diesel vehicle can be harder to find and this drives up the price.
Another consideration is that used or refurbished parts are generally more readily available for gas engines. As diesel engines gain popularity, however, the number of used parts on the market is also expected to increase. In general, diesel vehicles need maintenance and repairs less frequently, but when they do, be prepared for it to cost more.
Since the cost of repairing a diesel vehicle is likely to be higher, you can expect your insurance company to charge a higher premium for insuring the vehicle. On average, the difference is about 10-15% more than insuring a comparable gas-fueled vehicle.
There are many reasons you may find yourself needing to sell your RV. You may need or want to stop traveling for a while, or you may find that your preferences change and you would like a rig that is a different size or offers different features. Diesel RVs have a higher purchase price but also a higher resale value. They depreciate less and are known for their longevity, making them easier to sell when the time comes.
Mountains and Steep Grades
The performance differences between a diesel and a gas RV are never more clear than when climbing a steep grade, such as when you are crossing the mountains.
Diesel engines are strongest at lower RPMs so they are ideal in any situation that calls for a lower gear. In a gas RV, when you can almost hear the sluggish engine chanting, “I think I can, I think I can,” all the way up the hill, you might just be left in the dust of a diesel RV that knows it can, no questions asked.
Torque vs. Horsepower
At the risk of conjuring unpleasant flashbacks to high school physics class, it’s important to know that torque and power are related but different. Torque is the capacity to do work, and power is how quickly the torque can be applied to complete a task.
You need both, but the question is which you would rather have more of. A diesel RV will give you more torque, meaning it is stronger when it comes to pulling a heavy load but a gas engine gives more horsepower, meaning it can accelerate faster and perform better at higher RPMs. Each of these is useful in different situations, so it is a matter of prioritizing what you need or want more.
Tow Rating and Weight Capacity
Because a diesel engine delivers more torque, diesel RVs have a higher tow rating than gas RVs. For example, a Class A gasser might have a tow rating of about 5,000 lbs, whereas a similarly sized diesel pusher can tow twice or even three times as much.
For many RV owners, this single criterion is the deciding factor, especially if they already have a car that they plan to tow. RVers who are traveling long-term also appreciate that diesel rigs often allow them a higher weight capacity for filling those storage compartments with cargo.
Cold weather performance is one of the few performance categories where the gas RV outshines a diesel RV. Gas engines are less sensitive to cold temperatures than diesel engines.
While newer diesel engines have made strides to improve their performance and ability to start when cold, the fact remains that diesel fuel begins to thicken and gel below about 40°F.
The colder it gets, the worse of a problem this becomes. There are additives that can help lower the freezing point of diesel, but if you plan to spend a lot of time in very cold climates, this is a factor to take into account.
Altitude affects the performance of any engine, and there is a popular myth circulating that gas engines perform better than diesel engines at higher elevations. Scientists, including engineers at MIT, have proven that this is indeed a myth. A diesel engine is actually more efficient than gas at high altitudes.
If you’re sticking to major highways and interstates, you’ll probably find plenty of large chain service stations with both gas or diesel motorhome easily accessible. If you prefer to take the scenic route, however, the situation might look a little different.
If you’re traveling in small towns and rural areas, diesel fuel may be harder to come by. Depending on the size of your tank, you may be able to explore these areas without needing to fill up. Approximately 55% of retail stations in North America currently offer diesel, but since diesel vehicles are increasingly popular, this number is expected to grow in the future.
Maintenance and Repair Availability
The majority of small, local garages and mechanics still focus on maintaining and repairing gas engines. Finding an experienced diesel technician might not always be easy and might require you to drive – or be towed in the event of a breakdown – much farther to get the service you need.
Then again, you can often seek service for a diesel RV at a service station that primarily serves commercial truckers. These stations are usually easily accessible from interstates and major highways and are typically open around the clock.
Maintenance and Repair Frequency
Diesel engines are the clear winner here. The parts of a gasoline engine that most frequently need tune-ups, such as spark plugs, are not a part of a diesel engine. The diesel engine’s efficiency actually reduces the amount of normal wear and tear on the engine which reduces the frequency of standard maintenance.
The timelines for changing oil and filters are about the same for gas- and diesel-fueled vehicles (consult your owners manual for information for your specific vehicle.)
Overall Longevity of the Rig
Well-maintained diesel engines generally last longer and can rack up more miles than a similarly well-maintained gas engine. The reasons have to do with how they’re designed, how they’re built, and how efficiently they run. There are many factors that influence the life expectancy of an engine.
There is no standard number but, as an estimate, if a gas engine can be said to average a lifetime of about 250,000 miles, then a similar RV with a diesel engine will probably surpass 500,000 miles.
Most RVers will not own their vehicles long enough to put hundreds of thousands of miles on them, but it is certainly a factor worth considering when purchasing a pre-owned rig.
This applies specifically to Class A coaches. A Class A gasser usually has its engine in the front of the vehicle, like most other vehicles. This means that the driver and passenger will be hearing engine noise throughout the drive.
In contrast, diesel Class A motorhomes typically have their engine in the rear. This is why they are often referred to as ‘diesel pushers’. Engine noise in the rear means a quieter ride for you upfront.
Moving the engine to the rear also means that most diesel pushers have the front pair of tires behind the driver’s seat rather than in front of or directly beneath it. This changes the way the coach handles on the road and significantly improves the turning radius.
Availability and Common Types of Motorhomes
Different types of motorhomes are simply more commonly made with one type of engine or another. Whether you are shopping for a new or a pre-owned RV, it may not be easy to find the class and size rig you are interested in with the type of engine you prefer. This is also a factor to take into consideration.
It is not difficult to find Class A motorhomes with both diesel and gas engines. Longer rigs are typically heavier so if you want a larger RV you are more likely to end up with a diesel engine by default, although larger gassers do exist.
Class B campervans are small and light, so many of the performance considerations are less of a concern. Until recent years, Class Bs with diesel engines were relatively rare, so on the pre-owned market, they are very difficult to come by.
As diesel engines gain popularity, manufacturers are starting to provide diesel options in their vans. Winnebago, Coachman, and Roadtrek are among the brands making diesel Class Bs. Otherwise, most Class Bs are running on gas engines.
The majority of Class C motorhomes are built on Ford E-series chassis. These are almost exclusively vehicles with gas engines. Finding a diesel Class C is highly unlikely, especially in the pre-owned market. The exception to this is the larger “Super Cs,” which are typically built on a Freightliner chassis (or similar) and often have diesel engines.
Tow Vehicles for Fifth Wheel and Travel Trailers
Fifth Wheel Trailers
Fifth wheel trailers are a type of towable RV that requires a specific type of hitch – called a fifth wheel hitch – that is mounted in the bed of a pickup truck. Because the hitch is so specific, these trailers can only be towed by a pickup.
While fifth-wheel trailers come in a range of sizes, with an average length of 32 feet, many of the most popular fifth wheels are between 38-42 feet long. Reasons for choosing this type of rig include that they tend to have taller ceilings, more storage space, and higher weight ratings for cargo.
All of these things make a diesel pickup truck the ideal tow vehicle for your fifth wheel. Can you tow it with a gas truck? Of course, if you choose a truck that is rated for the weight of your fifth wheel. Chances are, though, that you will appreciate the torque when you’re pulling that heavy load over the mountains, or backing up a slight incline into a campsite.
Travel trailers are the more traditional image of a “camper”. They are towed with a bumper hitch, and can, therefore, be towed by a variety of trucks or SUVs. Travel trailers come in a wide range of sizes, but in general, tend to be lighter and lower profile than fifth wheels.
Always double-check the specifications on your tow vehicle to be sure it can safely tow the weight of your trailer when it is loaded (consider gross vehicle weight and not just dry vehicle weight). Gas and diesel vehicles can both be used to tow a travel trailer well. Take into consideration all the factors listed above and make a choice based on which best fits your circumstances.
QUIZ: Will a Gas or Diesel RV Best Suit Your Needs?
Answer these 10 questions about your preferences:
1. How much do you plan to use your RV?
A. Full-time travel
B. Weekends and vacations
C. Long-term travel but not full-time
2. What type of RV are you most interested in?
A. Class A
B. Class B
C. Class C
3. Do you plan to tow a vehicle?
C. Maybe a small one
4. How long of an RV are you looking for?
A. As large as possible. Probably 35 feet or more.
B. As small as possible. I’d like to stay under 30 feet.
C. Somewhere in between. Maybe 30-35 feet long.
5. Do you plan to spend a lot of time in the mountains?
A. I love the mountains! The more the better!
B. There aren’t too many mountains ‘round these parts.
C. I’m not in the mountains much, but I’d like to visit sometimes.
6. Where will you be during the winter months?
A. Chasing 75° and sunny. I don’t even own a coat.
B. Can’t miss ski season! RV road trip in search of the best powder!
C. I love the deserts of the southwest, but it does get pretty chilly at night.
7. How tight is your budget?
A. I’m ready to spend whatever it takes to get what I want.
B. Like dress pants on Thanksgiving – not much wiggle room.
C. I’ve got margins but I’d rather spend less on the RV and more on experiences.
8. Which best describes your favorite places to travel?
A. I love cities for great museums, concerts, restaurants, shopping, and a reliable cell signal. I want to be in the middle of the action.
B. I want peace and quiet and natural beauty. Give me a mountain to climb or a sparkling lake to paddle across. I want to get away from it all.
C. I’d prefer a good balance of both. I tend to go back and forth.
9. Which is more important: eco-friendly or budget-friendly?
A. Eco-friendly! I want to reduce carbon emissions as much as possible.
B. Budget-friendly! Otherwise, I can’t afford to travel.
C. Is there a way to compromise and have both?
10. How long do you plan to keep your RV?
A. As long as possible. I don’t plan to change rigs anytime soon.
B. I’m not sure. I want to give RVing a try without making a huge investment.
C. For a while, but I’m open to selling it and upgrading if I see something I like better.
SCORING: If you chose…
A diesel rig is probably right for you. A bigger rig with larger tow capacity and a higher weight rating is more likely to suit your needs. You’re likely to stay where there is easy access to diesel fuel and service stations and you’re ready to spend a little more money to get exactly what you want. A diesel engine will be strong enough to keep up with your sense of adventure and last a long time so you don’t have to make this decision again soon!
You would probably be better off with a gas rig. You’re out for fun on a budget and you are less concerned about performance over mountains than you are about how much it will set you back to fill the tank. You’re happy in a smaller RV that can take you off the beaten path in any season without worries. If you have a little extra money to spend on adventures, you’d rather spend it on high-tech hiking equipment than a luxurious interior on your RV.
You’re going to be happy with either. Gas or diesel isn’t one of the primary factors for you in choosing your RV. If you find one you like with a gas engine, go ahead and get it. If a diesel pusher catches your eye, then get your checkbook ready. There are other factors that are more important to you than fuel, and your style of RVing will work well with either. When you meet your perfect RV, you’ll just know.
Fuel economy varies widely depending on many factors, including height, weight, age, maintenance, and whether or not you tow a vehicle behind your rig. Given all these factors, average mileage of 8-10 miles per gallon is a fair estimate for a diesel Class A motorhome. Gas engines will get slightly less.
Mechanically, a diesel RV can run well for 300,000 miles or more if properly maintained. There are many factors that can shorten or extend the lifespan of your rig, so be sure to read your owner’s manual, follow the recommended maintenance schedule, and take good care of your investment.
It is also important to remember that there are parts of your RV other than your engine that can wear out over time. Slideouts, generators, electrical systems, and plumbing are other important parts that also need maintenance. The interior of your RV may begin to be worn and need updating or replacing even while your engine still has plenty of miles left on it.
A gas RV should only be fueled with unleaded gasoline that is blended with a maximum of 15% ethanol, just like a gas engine on a car or any other vehicle. If your RV has a diesel-burning engine, you should only fill the tank with diesel. In recent years, there have been flex-fuel RVs introduced to the market, and these can also be fueled with E85 (85% ethanol).
Size matters when it comes to efficiency. Reducing weight and height increases fuel economy significantly. Age also plays a factor, of course, as newer engines are able to give great performance with less fuel.
Generally speaking, the most fuel-efficient gas and diesel RVs are late model Class B motorhomes (campervans), which have an industry average of 18-25 mpg. Class C motorhomes come in second place, and their industry average ranges between 14-18 mpg. Bringing up the rear are the tall and heavy Class A coaches, which have an industry average of about 7-13 mpg.
The answer to this hotly debated question is, of course, that it is a matter of preference. Which type of motorhome is better for you depends on your circumstances and your travel plans.
There are many happy RV owners on the road who are satisfied diesel RV owners and at least as many who are enjoying their gas RVs. Whichever type of RV (Gas or Diesel Motorhome)you choose, the important thing is not what’s in your tank but that you take the opportunity to get out there and explore!
Save 50% on Roadside Assistance RV Plans (for New Members Only) with this special offer from Good Sam.