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Fuel for Thought: Diesel vs. Gasoline in Motorhome Chassis

By Bryan Henke, manager, product marketing at Freightliner Custom Chassis Corporation

One of the first questions we at FCCC tend to hear from prospective RV owners is whether there are significant differences between diesel-powered chassis and those that run on gasoline.

It’s a good question. Gas engines were the motorhome industry standard for decades, and it was only about five years ago, in 2007, that diesel RV chassis sales surpassed their gasoline counterparts. And while it’s true that gasoline engines have seen some recent resurgence in the market, there are several reasons why diesel remains the better value and more oft-chosen option.

The chemistry of diesel fuel itself provides one reason: It has a higher energy density than gasoline, meaning that a gallon of diesel can generate around 11 percent more energy than a gallon of gasoline.

Diesel fuel also has a higher expansion ratio and combusts at a higher temperature within an engine piston, giving you – literally – more bang for your buck. According to the U.S. Department of Energy, diesel engines are on average about 30 to 35 percent more fuel efficient than gasoline engines of similar size.

Even looking at the U.S. Energy Information Administration’s recent data listing the average nationwide price of a gallon of diesel at $3.78, compared with $3.49 for a gallon of gasoline, the increased mileage afforded by diesel makes it the better value.

Diesel engines also offer greater torque ratings for the same horsepower as gasoline engines, meaning they’ll get your RV to cruising speed and climb hills with less effort. And they provide this additional power at a lower rpm rate, leading to better fuel economy – a gas engine will rev much higher and work much harder on mountain roads.

Maintenance intervals associated with diesel engine ownership are also much greater than those of gasoline engines. A diesel engine is typically scheduled for maintenance every 15,000 miles, compared with the 3,000-mile intervals of a gasoline engine. For owners, that’s more time on the road, lower maintenance costs, and less time spent in service centers.

And because they have fewer moving parts, diesel engines are more durable, with a life expectancy nearly three times that of a gasoline engine.

All these advantages add up over the long term, and when the time comes to upgrade your motorhome, you’ll find that diesel-powered RVs retain a higher resale value.

Power, efficiency, convenience and long-term value: Diesel edges gasoline on all four points – and who doesn’t want all that in an RV chassis?

Feel free to contact us by commenting on this blog post with any feedback or ideas you may have about FCCC customer support. FCCC enjoys speaking directly with our customers, and we want to make it as easy as possible for you to get in touch. You can also find us on Twitter @DriveFCCC, check out videos on our YouTube channel, visit our RV Road Trippers Facebook Page and email us at  

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About Greg Gerber

Greg Gerber is a freelance writer and podcaster who has been writing about the RV industry since 2000. He is the former editor of RV Daily Report.


  1. I must disagree w/this statement: “A diesel engine is typically scheduled for maintenance every 15,000 miles, compared with the 3,000-mile intervals of a gasoline engine”. That would be 15,000 miles, OR ONE YEAR. To my knowledge there are no OBD II gas cars that require a 3k mile oil change. Three of my gas powered cars have a computer to tell me when to change the oil, typically 6-8k miles, or for me, ONCE A YEAR. We have a 42′ diesel rig, and have had two gas rigs. Maintainance on the gas rigs were much less expensive. However, I would NOT give up my diesel rig, under any circumstances.

  2. What about the price of oil changes and filter changes for a diesel? Much more expensive than gas. Also there seems to be more warranty issues with a diesel chassis than a gas Ford chassis. Of course the diesel drives better but you also have to look at resale value which I think the gas is better because of the lower selling price.

  3. Diesels typically hold about a gallon more oil than gas. If you do your own maintenance, that’s only $14 more, if you use Delo 400.

  4. I strongly agree with riggarob. My 40 foot diesel pusher is much more expensive to maintain than previous gas coaches. In practice, both need an oil change once a year, but the diesel is much more expensive (and I do it myself). Ditto for air filter, radiator coolant, the need for SCA monitoring in coolant, regular changes of fuel filters, etc. I’m a diesel fan, but not because it is less expensive to operate.

  5. What diesel Rv hold only a gallon more oil than a gas unit Rob? Typical gas is 7 qts, typical diesel is 23-26qts. And yes you get better fuel economy (mind you that difference has been diminishing with all the new emission requirements) but at the increase initial cost and the higher depreciation, that is quickly lost. Diesels have their place, but to try to say that it is a better solution than a gas is rediculous.

  6. Can anyone tell about how many gallons of diesel a 40′ pusher holds, and aprox MPG?

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