Diesel fuel economy is a lie . . .

[Kenneth Brown]

Re: Diesel fuel economy is a lie . . .

I may be missing the point entirely but will throw in my 5 cents. I have 4 vehicles at the house. The wifes 5.4 Expi, my 2.0 elantra, these are our daily drivers. Then my farm trucks. I have a 89 F350 351W with 5 spd and 4.11 gears and a 94.5 F250 Powerstroke 5 spd with 3.55 gears. The gas motor will actually start out better but becomes a dog after about 40 mph. The diesel doesn't like its gear but as soon as it starts rolling (maybe 2-3 mph) I can pull anything you want to hook to it. When pulling the 5X16 stock trailer or 16' bumper pull its usually the Expi or the gasser. The expi gets around 14 or so while the gasser gets 8-9 if I'm lucky. These loads tend to be less than 4000 pounds. When I hook up the gooseneck I tend to either have a full load of scrap, hay, or the tractor. This load will weigh around 12,500 or so. The diesel will get rolling and consistantly get 12 mpg while running as fast as you dare push it. If it has the lighter loads I tend to get about 17-18 which is the same as if it was empty. For me I NEED the diesel to do what I need done. The gasser just won't perform to my needs.
The diesel has about 253,000 on it while the gasser has 147,000. The gasser has had some normal wear and tear with nothing major ever happening. The diesel has never had anything major either but its seems to have quite a few nickel and dime type of repairs that you wouldn't expect. I'm currently waiting on a fuel pump for it because of some trash in the fuel. There is no filter before the primary pump and it makes ya say humm... It'll get one before the new pump goes on for sure. For me neither truck is perfect for what I need but if I had to choose I'd keep the diesel.

PS- I sure like hitting about 2700 RPM and hearing that turbo whistle.

 

[DJ]

Re: Diesel fuel economy is a lie . . .

KB,


In your case, you're 100% correct. The diesel will outperform the gas, with major loads. Diesel technology is at least a decade behind gas.

Diesel will always be the ticket for anyone that needs MAJOR torque. Remember, "torque" gets a load moving, "horsepower" keeps it moving/rolling.

Let me use this example. A Ford V-10 gas is about 100 lb. ft. shy of torque compared to the 6.4L Powerstroke. However, the horsepower is about the same.

The diesel will get it going, quickly, once rolling the gas and diesel become close in MPG.

The "emissionized" diesel simply is not as efficient as it used to be. MPG ratings for highway driving between gas and diesel are becoming close to one another.

 

[QC]

Re: Diesel fuel economy is a lie . . .

And I am kinda simply talking cost to make horsepower . . . although I am also thinking fuel cost has spread enough that longevity doesn't matter much either. Today I think you can make a case for gasoline. Never before that I am aware in the US . . .

Also, gear reduction can make a difference in start torque i.e. a 6 speed auto with deeper reduction on the gas example could nullify some of the torque discrepancy as ultimately it is wheel torque we are concerned with. Very hard to make this discussion apples to apples, but a 45% difference in fuel cost is significant regardless of how you slice it.

 

[DJ]

Re: Diesel fuel economy is a lie . . .

QC,

Good point on "gears".

With todays 5 and 6 speed transmissions (double OD). It does make the equation more interesting.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

Well, I'll put it this way....I work at a Dodge dealership as a lead tech.......I'm also the leading diesel specialist. When I needed a new vehicle to tow my 7 or 8000 lb boat and trailer, I bought a Chevy with a 8.1 litre gas engine. It was a no-brainer as far as I'm concerned. And this was even though I can get Chrysler employee pricing which means I can buy that Dodge diesel truck for about 16 grand less than sticker. I regularly tow in excess of 2 hours each way in a mountainous area and I go to the Outter Banks at least once a year--a ten hour trip for me. The Dodge diesel was a consideration for about .5 seconds. And I do like the Cummins diesel...for my money its the best one on the light truck market.

 

[Limited-Time]

Re: Diesel fuel economy is a lie . . .

Well, I'll put it this way....I work at a Dodge dealership as a lead tech.......I'm also the leading diesel specialist. When I needed a new vehicle to tow my 7 or 8000 lb boat and trailer, I bought a Chevy with a 8.1 litre gas engine. It was a no-brainer as far as I'm concerned. And this was even though I can get Chrysler employee pricing which means I can buy that Dodge diesel truck for about 16 grand less than sticker. I regularly tow in excess of 2 hours each way in a mountainous area and I go to the Outter Banks at least once a year--a ten hour trip for me. The Dodge diesel was a consideration for about .5 seconds. And I do like the Cummins diesel...for my money its the best one on the light truck market.

SN, can I ask why?? Unless it's also your daily driver. I know the Cummins will deliver both better millage and pulling power using it as you described.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

SN, can I ask why?? Unless it's also your daily driver. I know the Cummins will deliver both better millage and pulling power using it as you described.

Several reasons, really.
1. The fuel mileage averages about the same (I know you won't believe it, but I get 18 mpg on the highway even when towing) and gasoline is cheaper and more readily available. Plus, my gas engine has more acceleration in reserve at highway speeds.
2. Chevy trucks feel tighter at 100k than Dodges do at 50k, with fewer suspension problems and they stay tighter than Dodges
3. Big-Block Gas engines have a much broader RPM range than diesels
4. Typical diesel repairs (if there is a problem) are VERY expensive, even at my cost.
5. With the gearing they use currently, even with the newer 6-speed transmissions, running a diesel down the highway at 3000 rpm for hours on end is just too disconcerting for me. The trucks I work on get roadtested on the highway a lot and I don't like the way 70 mph is 3/4 of the way or better to redline.
6. Dodge doesn't make a Suburban with a big-block or a diesel.
7. Chevrolet doesn't make a Suburban with a diesel.
8. If I was plowing all the time or doing other low-speed high torque applications where you need the power to be there right off idle. Then I would think about buying a diesel...notice I said THINK about it. But any highway work, I'll stick with the gas engine and just get one big enough to give me the torque I need down low. If I didn't need the torque, I'd have gone with the 6.0 or the 5.3.


And it would be very important to note that it required a 8.1 litre gas engine to come close to matching the torque of a 5.9 or 6.7 litre diesel engine.

None of this is either fact or conjecture, it is however, based on personal experience (as a mechanic, I have wonderfully lucky access to many different vehicles) and as such it is my personal opinion and should be taken as such.
P.S. No, It's not my daily driver......that's a '91 Ford Mustang GT.

 

[Limited-Time]

Re: Diesel fuel economy is a lie . . .

Thanks for the reply SN. My daily driver is a 02 F 250 Super Duty Super Cab 4X4 with the V10 and 4:33 gears. Having done the cost comparison before buying the numbers are not good for a diesel for a daily driver. They do however change if you're constantly towing a heavy load. Say 75% of the vehicle's max. I'll look around and see if I can find my actual numbers and post them.

BTW FWIW I average 15 t0 17 MPG on the freeway IF I keep it under 70 MPH or so. If I start pushing it the millage drops off fast.

 

[QC]

Re: Diesel fuel economy is a lie . . .

Like Nova, I have been around diesels for the last 30 years. I used to say that I know waaaaay too much about diesels to own one . . .

That came from a couple of things, but mainly repair costs.

I will say that the later, small displacement, high RPM (4 - 5000) european diesels are amazing. Fun to drive, wide operating range, especially cool with a manual trans. I love their fundamentally better efficiency. I love how they sound. I also love all turbocharged engines. Oh, and another funny point, if you buy into CO2 and Global Warming etc. then running diesels would make us more "green".

But today, with fuel prices as they are, most applications theoretically have a higher operating cost with diesel vs. gasoline.

 

[mthieme]

Re: Diesel fuel economy is a lie . . .

Okay, but if the Dodge diesel gets 50% better mileage that the Chevy 454, and you say fuel costs 40% more.......sounds like I'm ahead of the game by 10%.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

Thanks for the reply SN. My daily driver is a 02 F 250 Super Duty Super Cab 4X4 with the V10 and 4:33 gears. Having done the cost comparison before buying the numbers are not good for a diesel for a daily driver. They do however change if you're constantly towing a heavy load. Say 75% of the vehicle's max. I'll look around and see if I can find my actual numbers and post them.

BTW FWIW I average 15 t0 17 MPG on the freeway IF I keep it under 70 MPH or so. If I start pushing it the millage drops off fast.

I'm with you with the speed thing for sure!! Any kind of heavy footing and the gas mileage suffers profoundly. In my case, most of my daily driving is done around town and in that instance, gas mileage is horrible with the beast. Like around 6 or 8 mpg. That's why I drive the Mustang. But anytime I go for a distance on the highway with more than just myself and maybe one other, with or without the boat, I take the Suburban. It's much more comfortable and very safe feeling.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

Like Nova, I have been around diesels for the last 30 years. I used to say that I know waaaaay too much about diesels to own one . . .

That came from a couple of things, but mainly repair costs.

I will say that the later, small displacement, high RPM (4 - 5000) european diesels are amazing. Fun to drive, wide operating range, especially cool with a manual trans. I love their fundamentally better efficiency. I love how they sound. I also love all turbocharged engines. Oh, and another funny point, if you buy into CO2 and Global Warming etc. then running diesels would make us more "green".

But today, with fuel prices as they are, most applications theoretically have a higher operating cost with diesel vs. gasoline.

Couldn't agree more with all the statements here. We have the VW line here as well as Mazda and Dodge and the import turbo diesels are awesome.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

Okay, but if the Dodge diesel gets 50% better mileage that the Chevy 454, and you say fuel costs 40% more.......sounds like I'm ahead of the game by 10%.

If those are the only factors you consider then in your example you would be correct. The key word to your statement is "IF"

 

[mthieme]

Re: Diesel fuel economy is a lie . . .

Poor wording on my part - the "IF" could easily go. Which truck to use when pulling anything long distance at highway speeds is a no brainer for my wallet.
QC's original post simple taking into account only maintenance over the life cycle. Obviously there are way too many factors to take into account to compare apples to apples.

 

[SuperNova]

Re: Diesel fuel economy is a lie . . .

Poor wording on my part - the "IF" could easily go. Which truck to use when pulling anything long distance at highway speeds is a no brainer for my wallet.
QC's original post simple taking into account only maintenance over the life cycle. Obviously there are way too many factors to take into account to compare apples to apples.

I know but my point was that the diesel doesn't get 50% better fuel mileage. That's why the "IF" was so important. Everybody thinks that the extra cost of diesel fuel is offset by it's increased fuel economy and as QC proved, that's just not true.

By the way, I don't know if your example was directed towards my example, but if it was, the 454 is a 7.4 litre and the 8.1 litre is actually 496 ci. Not trying to be rude, just trying to clarify some possible confusion.

 

[QC]

Re: Diesel fuel economy is a lie . . .

Okay, but if the Dodge diesel gets 50% better mileage that the Chevy 454, and you say fuel costs 40% more.......sounds like I'm ahead of the game by 10%.

Absolutely agree . . . With two caveats:

1) You said if, it depends on what the definition of if is . . .

2) You are only accounting for operating costs, needs to be a complete owning and operating cost analysis to be 100% valid. Purchase differential, repair costs, and trade value.

Trade value could tip it in the diesel's favor alone. Many that talk longevity trade before either the diesel or the gas engine needs an overhaul so that is meaningless to those specific people.

OT: Did I use caveat right? :redface:

 

[QC]

Re: Diesel fuel economy is a lie . . .

LOL . . . I was sitting on that screen for a while and didn't see Nova's if comments . . .

 

[Bob_VT]

Re: Diesel fuel economy is a lie . . .

I am a very big fan of diesel and wish that I had one. I have had in the past diesel trucks, cars and an suv..... every year the technology gets better.

I say that but at present I own all gas vehicles including a 3/4 ton truck. The sad part about being in this part of the country is the engines normally outlast the vehicles. Trade value around here (cold climate) is bad on most any vehicle regardless of engine. It is what the market will permit.

I looked into propane and asked around..... people reacted like that was not even a possibility........ here in VT they are behind the technology curve.

 

[QC]

Re: Diesel fuel economy is a lie . . .

Propane does not like extreme cold . . . Loses fuel pressure . . .

 

[mthieme]

Re: Diesel fuel economy is a lie . . .

LOL . . . I was sitting on that screen for a while and didn't see Nova's if comments . . .

I think you're original statement was over simplistic.
There are so many factors that we'll be beating to death for a few more pages yet. Whenever we get clean diesels for cars, that might change the landscape.
I just had to get my 2 cents worth in.