So, what *really* makes for good interstate fuel economy?

Rupert wrote: In reply to curtis73: I've read more than one or two treatises that say the best throttle position with conventional carbs. is wide open while pulling the highest gear possible. You're operating as close to engine stall speed as possible. This results in a higher air to fuel ratio since the suction which draws the fuel is hugely reduced. But watch out for compression knock!! Pin holes in pistons can get expensive.

While that is true for thermal efficiency (getting the highest amount of BTUs out of the fuel) it is still moving WAY more fuel than small throttle openings. Thermal efficiency is high, but MPGs drop to the single digits.

iceracer wrote: Gas vs. diesel. Cost per mile is the question or maybe the answer. Ruling out the hit of buying the diesel.

Why doesn't anyone consider resale value?

From the time you buy to the time you sell, Diesel vehicles almost always keep way more money in your pocket than gas vehicles. At least if they don't, the owner paid too much or sold too low.

Keeping fuel in it is cheaper, (mpgs vs cost per gallon) resale is almost always higher, maintenance is usually on par. They take a little more in oil changes and fuel filters, but don't ever need plugs, wires, etc.

In order for a diesel to be cheaper on fuel, it only needs to get 27% better MPG to match fuel cost per gallon of a gas counterpart. Most diesels have that and more, especially trucks.

maj75 wrote: What pisses me off is how the government has conspired with the auto companies to keep the price of diesel higher than gasoline. There is absolutely no production reason that diesel should cost more than gas.

Agreed. Diesel is cheaper and safer to produce, cheaper and safer to transport, easier to store, more stable in storage... It should cost about 63 cents on the dollar compared to gas.

The big reason though isn't auto makers, its trucking. Diesel is a requirement. If big trucks ran gasoline, it would be the more expensive fuel. States tax the diesel to get the money premiums of big trucks using their roads. Some states charge different diesel prices for Auto and Truck.

Knurled wrote: I fully expect tightening emissions laws to make Diesel powered private vehicles no longer viable to produce as new cars in 10-15 years. Too expensive to make clean. I would not be surprised if the number of people circumventing the emissions controls resulted in private ownership being made illegal.

I think it might surprise you. As of 2008, light and medium diesel now conforms to the same emissions standards as gas. Cummins already has a 12.8L truck engine that meets Euro standards without EGR or Urea injection for use in 2016 trucks. Diesel engine manufacturers see the writing on the walls and they are really staying ahead of it.

yupididit wrote: One time in my ecoboost fusion I was able to cruise at 60mph via cruise control for about 90 miles none stop. The car said was getting 45mpg and at one point 49mpg going down hill. But, I'm sure it was more like 38mpg. I wonder how the car computer calculates its mpgs.

Yup... it knows fuel pressure, delivery rate of the injectors, and the pulsewidth its telling the injectors to be open. The only one of those on-board MPG computers that I ever experienced that was close was in my e30, but it was only accurate because I had smaller diameter tires and didn't correct for it.

The actual amount of time the injectors are open is rarely exactly what the computer tells it to do. It takes time for the injector to open and close before and after the signal from the computer. This effect is exaggerated at lower RPMs. It makes those computers pretty optimistic.

In reply to 93gsxturbo:

I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K.

Resale on diesels can be significantly more.

curtis73 wrote:

Knurled wrote: I fully expect tightening emissions laws to make Diesel powered private vehicles no longer viable to produce as new cars in 10-15 years. Too expensive to make clean. I would not be surprised if the number of people circumventing the emissions controls resulted in private ownership being made illegal.

I think it might surprise you. As of 2008, light and medium diesel now conforms to the same emissions standards as gas. Cummins already has a 12.8L truck engine that meets Euro standards without EGR or Urea injection for use in 2016 trucks. Diesel engine manufacturers see the writing on the walls and they are really staying ahead of it.

Diesels are clean, sure. But the EU rules are very different than the US rules- they bias the law to favor diesels in a pretty big way. At least for a few more model years. Unless there's some major development that happens in the next 5 years, the EuroVI emissions rules lower the diesel requirements that I see the day's of the B and C class diesels going away (except for the luxury lines). Perhaps even the C/D cars.

As for the US- that change will have to be really big- as by 2023, the US Fleet average for emissions will be PZEV. While it's been demonstrated that diesels can make the PZEV number, the cost to do that is massively high. Right now.

Oh, and my hint for good highway mileage- drive calm.

You can go and find that car that has the best thermal efficiency over others, but you still need to drive calm.

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave way more money in my pocket.

alfadriver wrote: Oh, and my hint for good highway mileage- drive calm. You can go and find that car that has the best thermal efficiency over others, but you still need to drive calm.

This. I have a commute that favors good MPGs. I drive 88 miles each way, 18 of them at on surface streets, the rest on I-75 usually before the nasty traffic hits. When I've been able to get a full tank of calm driving I've seen 735 miles before the low fuel light came on. That tank was about 53 mpg. I've also had weeks where I just didn't care and saw 100 miles less to the tank, or 45 mpg. I don't necessarily drive slow (70-75) but I do everything I can to keep my throttle inputs small, I try to time acceleration to down hill sections. Around town I accelerate to keep up with traffic.
I'd like to see what I could get if I was hyper-miling.
BTW, this is all with a 99 Golf TDI with 270K on it.
But, back to the original post. The best long distance hauler was my diesel benz. 33 MPG with ease and seats that we made for my bootyus maximus.

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

iceracer wrote: In reply to wbjones: Some of the extra cost of diesel fuel may be the cost of producing the new environmentally devoted fuel.

that wasn't the "excuse'' 20 yrs ago … diesel has always been more expensive in most states … to which I still attribute the taxes being the cause …

but you're right, the added expense of making it cleaner probably does add to the cost

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

but a replacement gas motor would still leave $$$$ in the gassers pocket … diesel is great, if the need is there .. but sometimes it's hard to justify the added upfront cost, the added price of fuel (unless you're accustomed to 93 octane price) … regardless of the re-sale value … especially since I tend to keep vehicles 10+ yr

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

You're neglecting that either truck in the rust belt, given typical mileage growth, will have late stage terminal cancer(among other issues) by the time the gasser is used up(and a LSx or later production Ford 2/3 valve is going to go longer than 200k if cared for). Diesel trucks make sense if you're towing huge loads often and putting 20k+ miles a year on it.

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

First of all, the gasser is not worthless @ 200k. But a lot of these assumptions are fairly exaggerated, so what the hell.

A Kenny said, if you don't tow heavy loads often or drive a lot of miles, the Diesel isn't really worth it.

At the rate I would put mileage on a truck it would take me more than a decade to get from 150-200k anyway. In that time, the additional $11k saved over the diesel would earn me another $11k invested - far more than the additional $1k in depreciation (unlikely anyway) and the additional gas costs (unlikely to be large as I'm not towing heavy [any?] loads) Not to mention less in insurance because... not going to carry full coverage on a cheap gas truck vs. a diesel.

wbjones wrote:

iceracer wrote: In reply to wbjones: Some of the extra cost of diesel fuel may be the cost of producing the new environmentally devoted fuel.

that wasn't the "excuse'' 20 yrs ago … diesel has always been more expensive in most states … to which I still attribute the taxes being the cause … but you're right, the added expense of making it cleaner probably does add to the cost

diesel fuel was cheaper than gas around here until about a decade ago- sometimes a lot cheaper- when it suddenly became a dollar a gallon more expensive than gas almost over night.

wbjones wrote:

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

but a replacement gas motor would still leave $$$$ in the gassers pocket … diesel is great, if the need is there .. but sometimes it's hard to justify the added upfront cost, the added price of fuel (unless you're accustomed to 93 octane price) … regardless of the re-sale value … especially since I tend to keep vehicles 10+ yr

Wait... hasn't this been covered already? The fuel could cost $4.50 and still put money back in your pocket. There is no "added price of fuel" when you are using proportionally less fuel than its additional cost per gallon.

How do you figure a new motor still puts money in your pocket? The whole point is that the resale puts thousands back in your pocket with diesel to start with... so on a gas vehicle which is already losing you money on resale, how does a $1500 engine replacement make the gas a better bet?

Not to mention, if you keep your vehicles 10+ years, a diesel has already paid for itself twice over with the fuel savings.

Comparison. Buy a new or slightly used gas truck for $20k. Drive it for 15 years and 200k. You now have a $4000 truck. Or, buy a new or slightly used diesel truck for $25k. Drive it for 15 years and 200k, keep more fuel money in your pocket, and sell it for $12k. Which one puts more money back in your pocket? How would replacing a gas engine make that deal sweeter?

I know I've told you all this story before, but I was a fleet maintenance manager for a utility company. We had about 130 diesel trucks at any given time and somewhere around 25 gas trucks for bosses, parts runs, support vehicles, etc. With the exception of about 3 6.0L Powerstrokes, diesel was the absolute, clear winner in keeping money in the company's pocket. and I'm not saying just a little bit, I'm talking about thousands of dollars per vehicle... including maintenance, repairs, fuel cost, fuel filters, oil changes, tires, headlight bulbs, everything. Sometimes it accounted for a swing of $10,000 on a single vehicle compared to its gas counterpart. Every single penny was accounted for right down to air fresheners and fuses.

I realize I'm talking about 3/4-ton up to 1.5 ton trucks, and also realize that it doesn't always equate to TDIs or Mercedes, but I get so tired of hearing all the old money arguments about diesels.

Show me someone who won't buy a diesel because of the money, and I'll show you someone who most likely failed basic math.

alfadriver wrote:

curtis73 wrote:

Knurled wrote: I fully expect tightening emissions laws to make Diesel powered private vehicles no longer viable to produce as new cars in 10-15 years. Too expensive to make clean. I would not be surprised if the number of people circumventing the emissions controls resulted in private ownership being made illegal.

I think it might surprise you. As of 2008, light and medium diesel now conforms to the same emissions standards as gas. Cummins already has a 12.8L truck engine that meets Euro standards without EGR or Urea injection for use in 2016 trucks. Diesel engine manufacturers see the writing on the walls and they are really staying ahead of it.

Diesels are clean, sure. But the EU rules are very different than the US rules- they bias the law to favor diesels in a pretty big way. At least for a few more model years. Unless there's some major development that happens in the next 5 years, the EuroVI emissions rules lower the diesel requirements that I see the day's of the B and C class diesels going away (except for the luxury lines). Perhaps even the C/D cars. As for the US- that change will have to be really big- as by 2023, the US Fleet average for emissions will be PZEV. While it's been demonstrated that diesels can make the PZEV number, the cost to do that is massively high. Right now.

I'm still very hopeful.

curtis73 wrote:

wbjones wrote:

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

but a replacement gas motor would still leave $$$$ in the gassers pocket … diesel is great, if the need is there .. but sometimes it's hard to justify the added upfront cost, the added price of fuel (unless you're accustomed to 93 octane price) … regardless of the re-sale value … especially since I tend to keep vehicles 10+ yr

Wait... hasn't this been covered already? The fuel could cost $4.50 and still put money back in your pocket. There is no "added price of fuel" when you are using proportionally less fuel than its additional cost per gallon. How do you figure a new motor still puts money in your pocket? The whole point is that the resale puts thousands back in your pocket with diesel to start with... so on a gas vehicle which is already losing you money on resale, how does a $1500 engine replacement make the gas a better bet? Not to mention, if you keep your vehicles 10+ years, a diesel has already paid for itself twice over with the fuel savings. Comparison. Buy a new or slightly used gas truck for $20k. Drive it for 15 years and 200k. You now have a $4000 truck. Or, buy a new or slightly used diesel truck for $25k. Drive it for 15 years and 200k, keep more fuel money in your pocket, and sell it for $12k. Which one puts more money back in your pocket? How would replacing a gas engine make that deal sweeter? I know I've told you all this story before, but I was a fleet maintenance manager for a utility company. We had about 130 diesel trucks at any given time and somewhere around 25 gas trucks for bosses, parts runs, support vehicles, etc. With the exception of about 3 6.0L Powerstrokes, diesel was the absolute, clear winner in keeping money in the company's pocket. and I'm not saying just a little bit, I'm talking about thousands of dollars per vehicle... including maintenance, repairs, fuel cost, fuel filters, oil changes, tires, headlight bulbs, everything. Sometimes it accounted for a swing of $10,000 on a single vehicle compared to its gas counterpart. Every single penny was accounted for right down to air fresheners and fuses. I realize I'm talking about 3/4-ton up to 1.5 ton trucks, and also realize that it doesn't always equate to TDIs or Mercedes, but I get so tired of hearing all the old money arguments about diesels. Show me someone who won't buy a diesel because of the money, and I'll show you someone who most likely failed basic math.

you totally missed what the post said … the gasser was a $4000 truck (at purchase time … not at sell time) with 150k and the diesel was $15000 … even with the difference in fuel efficiency AND the cost of a "new" motor the gasser would still not cost you more, until you put lots more miles on it than most fold will … that $11000 initial cost difference buys a lot of fuel AND a replacement motor

your scenario of a nearly new gasser and a nearly new diesel is accurate (I guess) … but not if your buying a 10+ yr old truck to start with

DrBoost wrote:

ProDarwin wrote:

NGTD wrote: In reply to 93gsxturbo: I was following an auction for a 2004 Dodge 3500 Dually with a Cummins TD recently. It sold for almost $15K. A similar Dodge with a gas motor went for $4K. Resale on diesels can be significantly more.

Look at that from the used-truck perspective. I'm planning buying a used 10yr old truck. A Diesel will cost me $15k, and a similar gas truck will cost me $4K. Unless this vehicle sees extreme usage, over the ownership of the vehicle the gas truck will leave **way** more money in my pocket.

But, let's say those trucks both have 150K on them. The diesel has a few hundred thousand miles left if it's been taken care of. The gasser, 50K?? At the 200K mark, the gasser is worth a nice cold pop, the diesel is still worth 12K.

That is the nice thing about living in salt land. Both examples would rust out before the drivetrains fail.

curtis73 wrote: I'm still very hopeful.

I wish I could say I was, too. But I'm not. I'm far more hopeful that gas emissions devices will get cheaper.

Hope based on progress.

Still, the argument is how to get the best highway fuel economy. Diesels have certainly shown their worth, but gas can do well, too.

curtis73 wrote: Wait... hasn't this been covered already? The fuel could cost $4.50 and still put money back in your pocket. There is no "added price of fuel" when you are using proportionally less fuel than its additional cost per gallon.

Except, the economy isn't there. My boss's Silverado gets 16mpg no matter what. At current prices, a Diesel would have to get 25mpg. And that is assuming he's not running it on $1.10/gallon equivalent CNG.

Comparison. Buy a new or slightly used gas truck for $20k. Drive it for 15 years and 200k. You now have a $4000 truck. Or, buy a new or slightly used diesel truck for $25k.

Those numbers are closer to $50k and $70k nowadays, no?

I think a good gas station can make all the difference...

before you tell me that they are regulated by the government for metering the correct amount of fuel and such (I know), I just think sometimes some gas stations are 'out' of calibration more than you think. Ever stop at a gas station that seems to have cheaper gas than everyone else? Ever get the feeling you always end up buying MORE gas at those places?

So therefore at the right gas station you buy 5 gallons and actually get 5, not 4.8... etc.

Personally I believe the fuel usage calculated by the car's computer is MUCH more accurate than the meter on most pumps, and let's face it, if you don't use the car's computer number, you have to use data that comes only from your pump's meter at the gas station.

This is starting to get around levels of porch building if it keeps up.

So keep it up

wbjones wrote: that wasn't the "excuse'' 20 yrs ago … diesel has always been more expensive in most states … to which I still attribute the taxes being the cause …

That's not true.

Prior to 2004, gasoline generally exceeded the cost of diesel at the pumps in the US. Diesel was cheaper.

The federal tax difference is $.06 per gallon.

The primary reason for the difference is an imbalance in manufacturing capability vs demand.

The US demand for gasoline has been declining since 2007. Diesel demand has increased.

The US refining infrastructure is optimized for the production of gasoline.

From October 2010 until October 2012, demand for gasoline decreased 3.4%, while demand for diesel increased 11.8%.

As demand for gasoline has shrunk, price of gasoline has shrunk. Meanwhile, the demand for diesel has risen, which would normally mean an increase in diesel cost, but our inverted manufacturing process has accelerated the imbalance and increased the price of diesel exponentially.