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Discussion Starter #1
I attended the Houston RV Show yesterday, and had the opportunity to discuss the ProMaster with a Winnebago representative who seemed knowledgable on technical issues. He was there to back up local dealers on new ProMaster products. Unfortunately Winnebago didn't have the new Travato at the show which was my primary interest, but did have two very nice Trend/Viva Class C or B+ units.

Anyway, while discussing fuel economy, I asked him about the Diesel engine option. He said Chrysler was completely surprised by the engine not meeting emissions requirements, and that he had no idea when it may be available.

Of interest to me was his comment that even if diesel was available, they were not certain they would use it for numerous reasons. Mainly, it adds a lot of cost. He mentioned between $7,000 and $8,000 which I quickly questioned. He correctly pointed out that in addition to RAM diesel option, a diesel generator adds over $3,000 over a gasoline generator of similar size. He said they can go with propane generator that is cheaper, but propane goes through fuel tank faster and is not as convenient to refill. Most buyers want to fuel generator off vehicle tank.

Another issue is diesel generator is taller and more difficult to package under low floor; particularly on Travato Class B van. The Class C Trend floor is higher and yields more ground clearance. Diesel generators also tend to be a little noisier.

Finally, he mentioned that the RAM diesel option adds significant weight, as does a diesel generator over a gasoline one. And on a RV that doesn't have great load-carrying capacity in the first place, this added weight can make a significant difference.

Because RVs generally don't get driven as many miles as commercial vans, payback on diesel may not be too attractive, particularly if buyer wants diesel generator instead of propane.
 

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Discussion Starter #3
interesting insight indeed. Has diesel ever been a popular choice for smaller RV's?
Yes, particularly within some segments. Just like with bigger units, diesel has been more popular with high-end units. Practically all Mercedes Sprinter camper vans are diesel, but they are generally higher cost. And not just due to van engine, but because the coach itself tends to be more upscale.

Before ProMaster there wasn't a great choice for budget high-roof van to compete with Sprinter, so it will be interesting to see how this unfolds. For a given size do RV buyers want luxury or value? I personally think there is a demand for both, but in smaller sizes I think initial cost will be more important. I expect PMs will do very well as they do in Europe (although there they are diesel). Much also depends on how much the owner plans to drive. Based on my shopping, smaller RVs tend to get driven more miles which may favor diesel somewhat.

Also, when Ford offered diesel vans, some upscale brands like Born Free, which made smaller RVs, seemed to sell a lot more diesels as a percent of their own volume than cheaper brands.
 

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Discussion Starter #5
3000 more for a small generator? Not sure I'm buying into that.
Apparently neither are many van camper buyers.

If you check pricing, a gasoline or propane runs around $4,000 installed, versus just over $7,000 for a 3KW diesel.
 

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Discussion Starter #8
Yeah, diesel costs can be higher in US. In this case the difference is hard to justify based on fuel economy because the average RV doesn't get driven that much.

On average RVs are driven around 5,000 miles per year, but I estimated based on 7,000 miles per year due to smaller RV size. I also assumed lower-than-expected fuel economy to make diesel look better.

7,000 miles at 14 MPG requires 500 gallons a year. At $3.50 that's $1,750 per year in fuel costs.

Assuming diesel gets 30% better MPG, or 18.2 MPG, that's 385 gallons per year. At $4.00 that's $1,540 per year in fuel costs.

Not even counting other diesel operating costs, $210 savings per year would require over 30 years to pay for added initial cost.

It's not even close. If van was driven twice as much, or 14,000 per year, it would still take over 15 years to break even. And that's assuming money has no cost.

I could justify a diesel just because I may want it -- like any other luxury -- but not on financial basis.
 

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Ok I'll admit I am wrong. Almost double for the cost of a generator that's a hard sell. I would go gas if is as looking at a rv. The more I read on here I'm not sure the diesel option is going to outsell the gas. For me the break even point is over 100k miles. The only thing I don't like about the gas setup is everyone saying its a minivan trans.
 

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I guess it depends on where you RV. If you are touring Rocky Mountain states, Appalacia, Green Mountains, etc, the diesel will have the edge in torque when the hills start & will maintain it's mpg better, and have less power dropoff at altitude (because it is a turbo).

Some PM gas owners have been griping about 8-11mpg on hills, & also complaining about transmission shifting up hills.
Imagine those traits magnified on an RV because they are highly loaded all the time.

The Winnebago rep brings up good points on component costs, but he's not gonna talk up the diesel option - cause they aren't selling them.

I think that diesel payback costs will happen much sooner in an RV, unless you are touring corn fields in Iowa.
 

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In Italy a vehicle with a 3.6 lt V6 gas engine is more expensive than another with a 3.0 liter 4 cilinder...
With the same displacemet and the same number of cylinders the diesel is a little more expensive than the gas engine. Often they are offered in promotion at the same price...
4000$ dollars of difference is incredible by me...
 

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Discussion Starter #12
I guess it depends on where you RV. If you are touring Rocky Mountain states, Appalacia, Green Mountains, etc, the diesel will have the edge in torque when the hills start & will maintain it's mpg better, and have less power dropoff at altitude (because it is a turbo).

Some PM gas owners have been griping about 8-11mpg on hills, & also complaining about transmission shifting up hills.
Imagine those traits magnified on an RV because they are highly loaded all the time.

The Winnebago rep brings up good points on component costs, but he's not gonna talk up the diesel option - cause they aren't selling them.

I think that diesel payback costs will happen much sooner in an RV, unless you are touring corn fields in Iowa.
Keith, your points are all true, but in all honesty insignificant to me at a personal level as it relates to making a decision.

First, when RVing I'm on vacation mode and not in a hurry. Couldn't care less if it takes an extra 22 seconds to go up a hill, not that it would. Torque feels good but horsepower climbs faster. And while you are correct a naturally aspirated gas engine will lose more power at higher elevation, the gasoline PM is starting out with almost 100 extra HP. It will lose some of that advantage but it's unlikely the lower-power diesel will ever outrun it uphill.

And when I see reports of 8 MPG up a hill or the transmission downshifting I wonder why anyone would expect something different. If a van needs two or three times more power to go up a hill, what should we expect?

For what it's worth, I've taken RV trips out west over the Rockies in gasoline RVs and have gotten better MPG in the mountains that starting out of flat-as-pancake SE Texas. For every uphill there is a downhill, and in mountains my average speed on back roads is much slower. And slow reduces wind drag which improves MPG.

So while you are correct on most points if taken on absolute basis, I'm not sure the average RVer would ever save $7,000 in fuel, whether flat terrain or mountains.
 

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...gasoline PM is starting out with almost 100 extra HP. It will lose some of that advantage but it's unlikely the lower-power diesel will ever outrun it uphill...
My experience with turbo and non-turbo Saabs back in the 80s showed a dramatic difference at altitude. Non-turbo I'd have to drop back to 3rd gear from 5th to go over Loveland Pass (12,000 ft.) just to keep up with the 18 wheelers. Wouldn't surprise me to see PM needing all 6400 rpm to make it.
Oddly, NA gas engines don't feel strained in that situation. RPM is high but cylinder pressure is low due to altitude. You just run out of rpm. I imagine an RV would be limited to 3rd gear max speed over mountain passes.
 

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How come diesel engines are always so expensive in north america?

they seem to be standard often in europe
Taxes in Europe are higher on gasoline engines in general and large displacement especially. They are trying to manipulate the market to achieve arbitrary mpg numbers.
I have heard it claimed that attempts in Europe to affect the gas/diesel balance is why gasoline is cheaper than diesel in the US. Europeans are incentivized to use diesel, so it increases worldwide supply of gasoline vs diesel. Not a petroleum engineer, but I believe as you vary refining methods to get a higher percentage of diesel from a barrel of crude, the costs go up. Cheaper to refine more crude and have excess gasoline to sell.
 

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...The only thing I don't like about the gas setup is everyone saying its a minivan trans.
Don't forget it's also used in the Lancer and 200! Vehicles that might be towed by an RV.
Hard to believe the bearings and gears were originally spec'd for long term duty under much higher average loads. I doubt they would be able to beef up any of the hard parts for the PM application without modifying the case. Problem is we won't know for some time if they actually hold up. On the plus side there will be lots of donor parts in junkyards.
 

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Discussion Starter #16
My experience with turbo and non-turbo Saabs back in the 80s showed a dramatic difference at altitude. Non-turbo I'd have to drop back to 3rd gear from 5th to go over Loveland Pass (12,000 ft.) just to keep up with the 18 wheelers. Wouldn't surprise me to see PM needing all 6400 rpm to make it.
Oddly, NA gas engines don't feel strained in that situation. RPM is high but cylinder pressure is low due to altitude. You just run out of rpm. I imagine an RV would be limited to 3rd gear max speed over mountain passes.
All engines are different because they breath differently -- some better than others -- but in general they are typically derated in the order of 3 to 4 percent per 1,000 feet above 1,000. At higher elevations temperature is usually a little lower, so it can offset some of the power derating. Regardless, on a high-altitude mountain pass a non-turbo (i.e. - naturally aspirated) gasoline engine can be derated around 40 percent or so. That would leave the 280 HP engine able to produce only 168 HP. And since turbo diesels have to be derated also, just not as much, the PM's V6 should still do OK compared to diesel. And as elevation drops below 10,000 feet the V6 should outperform the diesel in power.

Most important for me personally, I know that I won't need to push the engine to 6,400 RPM redline to go up a hill. Not unless I want to. As the driver I can decide to limit the engine to 4,000 RPM in the same gear and not rev up to 6,000 plus. I'll just go up the hill slower.

By the way, on my trip out west, I had 305 very tired Horsepower in a RV twice as heavy as many vans. The Rockies through Colorado were never an issue, nor was Tioga Pass going into Yosemite. The only time I would have wanted more power was climbing out of Death Valley going east towards Las Vegas. And the elevation wasn't that high, it was more about the steepness of the road.
 
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