Print 48 comment(s) - last by arnold2.. on Apr 5 at 3:29 PM

Gap in fuel efficiency and torque between diesel and gasoline engines is dwindling

Diesel engines are very popular around the world, and are used in both passenger and commercial vehicles due to their efficiency advantages over gasoline engines. In the U.S. passenger vehicle market, they’re largely relegated to heavy-duty pickup trucks (although companies like Volkswagen have maintained a diesel engine lineup for a few decades). 
However, diesel fuel averages roughly $0.36 a gallon more than regular unleaded gasoline in the U.S., which can erase some of the cost advantage.

While many diesel-powered vehicles do have better fuel economy than comparable gasoline vehicles, even that benefit is beginning to disappear. In spite of this, many automakers are preparing to launch diesel-powered cars in the U.S., including GM, Chrysler, and Mazda.

Volkswagen Passat TDI

Detroit News reports that diesel engines in cars no longer have a major advantage in torque and they don't offer significantly better fuel economy. Technology for traditional gasoline engines is improving and the gap in fuel efficiency and torque has vanished due to the proliferation of direct injection and turbocharging.

With this in mind, Ford, Toyota, and Hyundai are staying out of the diesel-powered car market; instead focusing hybrid technology. Hyundai Motor America CEO John Krafcik says that the cost of adding hybrid technology for the consumers about $1,500 compared to a cost of about $5,000 to add diesel power.
"When we ask if consumers are willing to pay that, they ask, 'What are you smoking?'" said Krafcik. "We all have great diesel engines available to us, but gasoline engines are growing."
However, Ford says that it is ready to begin offering diesel-powered cars in the U.S. if there is enough consumer demand

Source: Detroit News

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How do they figure
By FITCamaro on 4/3/2013 9:54:34 AM , Rating: 1
You look at a truck like the Dodge Ram that will be offered with a diesel. Better fuel economy with the same torque as a V8. Trucks like the Silverado HD and Ford F250 get much better fuel economy in diesel trim than their gas powered brothers.

The biggest thing with diesels preventing their fuel economy from being even better is the federal government. Emissions are so tight in the US that it kills the mileage.

RE: How do they figure
By lagomorpha on 4/3/2013 10:11:07 AM , Rating: 2
Emissions are so tight in the US that it kills the mileage.

Not to mention massively drives up their price. Somehow in the US it costs $5,000 extra for a diesel option but in Europe there's little price difference and often diesel is the cheaper option. Yes, diesel engines do have to be built much stronger than the equivalent gasoline engine but not nearly $5,000 worth of metal stronger.

RE: How do they figure
By Manch on 4/3/2013 10:17:00 AM , Rating: 2
In the US, you're basically paying for all the emmisions crap they tack onto the diesels. And then theres the urea too. Still in a truck that I use for hauling, I'll take a diesel over a gas engine any day of the week.

RE: How do they figure
By mcnabney on 4/3/2013 10:22:03 AM , Rating: 2
I agree that the $5k cost difference mentioned in the article is BS. While equivalently performing (in HP) engines will cost slightly more in diesel form, the $5k is just not true. Maybe this exec from Hyundai was looking at Ford price lists and saw that the largest diesel engine option in an F350 had a $5k premium, but neglected to also consider that it offered double the HP and torque over the stock engine?

RE: How do they figure
By Argon18 on 4/3/2013 10:23:34 AM , Rating: 1
Agreed. The other factor for diesels, at least in trucks, is that none of the Big-3 make their own diesel truck engines. Chrysler buys them from Cummins. GM buys them from Isuzu. And Ford buys from International (Navistar) and Cummins. So there's always going to be a higher cost differential when you're buying from someone else, vs. building it yourself.

For cars its a different story. Ford sells loads of diesel cars in Europe, and the cost is about the same as the gasoline models. Heck, even Chrysler sells diesel cars in Europe. Diesel PT cruiser, for example, and it costs the same as the gasoline version.

RE: How do they figure
By bchandler02 on 4/3/2013 10:51:26 AM , Rating: 3
Wrong. Ford never bought from Cummins (at least not in the F550 or smaller). They also haven't been with Navistar in a few years either. The 6.7 Scorpion in the current F series is 100% Ford.

RE: How do they figure
By Samus on 4/3/13, Rating: 0
RE: How do they figure
By Kazinji on 4/3/2013 9:53:26 PM , Rating: 2
But so few diesels get sold here so you have to recoup the cost of developing the diesel. Taxes on diesel fuel is higher in US. Where in EU diesel taxes are lower to encourage the use of diesel. Since so many diesel version of the of a model is sold in EU they can recoup the cost easily with a minimal mark up for extra materials.

RE: How do they figure
By Strunf on 4/4/2013 7:58:23 AM , Rating: 2
The EU taxes less diesel fuel cause it's mainly used by companies, at first diesel was only used on trucks and agricultural machines, that's slowing changing and I don't have any doubt they will either tax both gas and diesel at the same rate or make it different prices depending on the use.

RE: How do they figure
By lagomorpha on 4/4/2013 9:06:22 AM , Rating: 2
But so few diesels get sold here so you have to recoup the cost of developing the diesel.

Or, you know, this might be one case where the US EPA could actually work with whatever agencies are responsible for emissions controls in Europe to create unified emissions standards such that cars only had to meet one set of requirements instead of having to be approved seperately for both markets.

RE: How do they figure
By Jeffk464 on 4/3/2013 11:47:53 AM , Rating: 2
You left out another advantage of diesel, it is far less likely to burn if you get in a wreck.

RE: How do they figure
By lagomorpha on 4/3/2013 12:03:19 PM , Rating: 2
Which is the reason that all schoolbuses in the US are now required to be diesel but how many consumers actually would pay extra just to reduce their chanes of dieing in a fire? That's really a niche feature.

RE: How do they figure
By ianweck on 4/5/2013 11:24:43 AM , Rating: 2
I think the article is talking about cars, not trucks.

Modern Diesel Engines are fantastic....
By stevemcdermott on 4/3/2013 10:16:51 AM , Rating: 2
But very expensive. A Common rail rail holds a reservoir of fuel at 30k psi, that takes serious engineering, as do the piezo electric actuators that squirt precise amounts of fuel into the cylinder multiple times per cycle. My BMW 3201 (efficient dynamics version) has a 2 litre engine that gives me 163bhp, top speed of 143 mph and I can sometimes do over 800 miles on a tank of 60 litres(15 US gallons). Ford also make fantastic diesel engines in its factory in Dagenham, to the east of London. Do such engines make sense when gas is nearly free? Unlikely. I do a spreadsheet when I buy a new car. My 60 litre tank of diesel costs me $128 at current exchange rates.
Modern diesels are great to drive....

RE: Modern Diesel Engines are fantastic....
By drewsup on 4/3/13, Rating: 0
RE: Modern Diesel Engines are fantastic....
By fishman on 4/3/2013 12:04:09 PM , Rating: 2
Gas engines last a long time, too. My car has 221,000 miles, and it uses a quart of oil every 3000 miles. Engines (both gas and diesel) can last a very long time - it's usually the other items that end up needing replacement.

RE: Modern Diesel Engines are fantastic....
By GotThumbs on 4/3/2013 12:17:04 PM , Rating: 2
and it uses a quart of oil every 3000 miles

Your valves or piston rings are shot. You must leave a puff of smoke as you leave every stop-light.

So factor in the additional pollution you're contributing and the cost of a quart of oil to your "fuel" costs. Just because you have over 220,000 miles, does not mean your car does NOT need a rebuild.

Diesel engines have tighter precision and my cummings has a rebuild estimate of 300,000+. I have 134,000 currently and do NOT have to add oil to the engine between oil changes (every 7,000 miles with no heavy hauling).

I believe diesel engines are a more expensive option in the US, simply because its still a small % of buyers who choose the option. Dealers WILL take every oportunity to maximize thier profits....and those really interested in a diesel engine ARE willing to pay more for it.

As with hybrids...economies of scale applies to diesel engines as well.

Best wishes,

By FITCamaro on 4/3/2013 2:46:31 PM , Rating: 2
It's also that a lot of diesel vehicles are only sold in the highest trims.

By sorry dog on 4/3/2013 3:10:59 PM , Rating: 3
You must leave a puff of smoke as you leave every stop-light. So factor in the additional pollution you're contributing and the cost of a quart of oil to your "fuel" costs. Just because you have over 220,000 miles, does not mean your car does NOT need a rebuild.

That's a big exaggeration.

Assuming an average of 40mph and 2500 rpm for average motor speed...

Means it took 4500 minutes for 3000 miles and 5,625,000 power cycles.

And converting to cc's for measurement's sake....

945 cc's in a quart... 945/5625000 = .000168 of a cc per power stroke or .0035th of a cc per second.

so....yeah....let's throw him in jail for gross pollution.

RE: Modern Diesel Engines are fantastic....
By Samus on 4/3/2013 10:17:26 PM , Rating: 1
Dude I totally agree... I laugh my ass off every time someone says "engine only uses 1 quart between changes"

That's hella terrible. No engine should have measurable change in oil capacity, even at 10,000+ miles without an oil change. If you are losing oil, it's either leaking or burning, and both are signs of a problem. It isn't broken in, it's broken. You have likely lost oil pressure somewhere due to a leak or increased friction/load, which results in lost power and efficiency.

It's also very bad for the environment.

If its leaking, it's getting into the water supply. And we're not talking BP oil spill oil, this oil that's leaking contains hundreds of carcinogens from hundreds of different chemicals and their byproducts of combustion.

If its burning oil, it also contains carcinogens, and they are not only getting into the water supply, but the air people and plants breath.

It's completely irresponsible. If it is ever found out someone knowingly continued to drive a car that leaked or burned oil without fixing it, they should have their car booted until they fix it.

By sorry dog on 4/3/2013 11:35:15 PM , Rating: 3
Your being sarcastic right?

If not, were the hell are you people getting these ideas? Lost oil pressure? The engine uses 1 drop of oil in a minute and it's time to rebuild it, right?

Hell, some folks used to mix 100:1 2 stroke in their RX7's to help the apex seals.

At least in slightly older designs, a small amount of oil usage is completely normal. Something as small as a particle of carbon stuck on a EGR valve o-ring could cause that usage...

RE: Modern Diesel Engines are fantastic....
By Spuke on 4/3/2013 4:24:51 PM , Rating: 3
diesels a LOT fewer parts than a petrol engine
Which parts would those be?

By Samus on 4/3/2013 10:20:23 PM , Rating: 1
Are you kidding? Start with an entire ignition system...

Doesn't make sense
By Dorkyman on 4/3/2013 11:34:58 AM , Rating: 3
I'm a bit mystified by the premise of this article.

Diesels are BY NATURE more "efficient" than gasoline engines:

(1) No manifold vacuum
Gasoline engines are essentially vacuum-pump devices, constantly trying to pull in more mixture than the throttle butterfly allows. Efficiency is good only at full-throttle, lousy in high-manifold-vacuum conditions, such as idle.

(2) Higher compression ratio
By definition a higher compression ratio will deliver more efficiency.

(3) More energy per gallon
Not an engine characteristic per se but it still means more miles per gallon.

I can see a gasoline engine trying to minimize the idle inefficiency issue by shutting down at those times but even so I think diesel will always beat gas.

RE: Doesn't make sense
By russki on 4/3/2013 12:51:53 PM , Rating: 2
I agree 100%, this article is total BS.
You also don't have any spark plugs, wires, distributors, or coils to worry about.
I have a diesel F350 that came at a 8k premium over the gas engine. They have about the same hp but the diesel makes double the torque. I drove both, the gasser was a real dog compared to the diesel. I get about 12~15 mpg depending on my driving. This is a 8k pound truck on 35" tires.
I can only imagine what fuel economy the gas engine would get.

RE: Doesn't make sense
By Spuke on 4/3/2013 4:32:30 PM , Rating: 2
You also don't have any spark plugs, wires, distributors, or coils to worry about.
No you just have glow plugs, piezo-electric fuel injectors, HFCM's and VFCM's, FICM's, fuel filters, and EGR's.

RE: Doesn't make sense
By sorry dog on 4/3/2013 3:39:48 PM , Rating: 2
Especially item #3.

Diesel has around 10% more BTU's per gallon.

Which is part of the reason it costs more per gallon as some energy consumers (i.e. power companies) are more interested in price per unit of energy than a liquid volume measurement.

So...if you want a more fair comparison, then you should take that 10% in to account in a miles per gallon comparison.

RE: Doesn't make sense
By FITCamaro on 4/3/2013 11:24:16 PM , Rating: 2
Diesel costs more because less of it is produced in the states and the higher taxes.

RE: Doesn't make sense
By rhangman on 4/3/2013 6:08:58 PM , Rating: 2
Odd no mention of HCCI either. In theory that could get you fairly close efficiency wise.

diesel vs. gasoline?
By tracyterpstra on 4/3/2013 1:52:50 PM , Rating: 2
I just wish that straight comparisons were made between diesels and gasoline engines. How can you say that gas is catching up to diesel technology due to direct injection and turbocharging? Direct injection yes. Turbo charging? When you run a turbo on a gas engine you have to run super. That 93 octane fuel that I purchase is within pennies of diesel. My MazdaSpeed3 is an awesome car but it only gets 25-27mpg hwy (when I am playing nice). No, I think that I will be looking at a VW jetta diesel in the future (42mpg hwy).

RE: diesel vs. gasoline?
By lagomorpha on 4/3/2013 2:02:10 PM , Rating: 2
I just wish General Motors hadn't cancelled Saab's variable compression ratio technology just before it was ready. It would have allowed gasoline engines to run at very high efficiency 16:1 compression ratio while maintaining highway speed, and dropped as low as 8:1 at full throttle with the turbo fully spooled up. This would have allowed for turbocharged cars to run on lower octane fuel and significantly improved gas mileage while adding power.

Unfortunately GM is GM and there's nothing the old guys running the company hate more than updating their technology.

RE: diesel vs. gasoline?
By Spuke on 4/3/2013 6:16:54 PM , Rating: 2
You bought a Mazdaspeed3 hoping to save fuel?

RE: diesel vs. gasoline?
By iamkyle on 4/4/2013 12:16:20 PM , Rating: 2
Depends on perspective I guess.

I'm ditching my 2003 Cadillac DeVille for a 2011 Subaru WRX STI. Sure it's turbo and requires premium fuel, but my current DeVille also requires premium and gets 16-18 MPG highway.

RE: diesel vs. gasoline?
By PaFromFL on 4/3/2013 7:39:10 PM , Rating: 2
With turbo direct injection, you don't need to use premium gasoline. Direct injection cools the cylinders so that a higher compression ratio can be used with regular gasoline. The turbocharger yields a broad torque curve, like a Diesel, while still producing a lot of horsepower at higher revs (unlike a Diesel).

For example, the 2.0 L (122 cu. in.) Hyundai direct injected turbocharged engine produces
274 hp (204 kW) (premium fuel)
260 hp (190 kW) (regular)
275 lb·ft (373 N·m) @ 2,000–4,500 rpm (premium fuel)
260 lb·ft (353 N·m) (regular).

RE: diesel vs. gasoline?
By lagomorpha on 4/4/2013 7:35:04 AM , Rating: 2
It probably doesn't hurt that a lot of turbocharged engines tend to have a longer stroke in proportion to the bore because they don't need to rev to quite as high an rpm to produce sufficient power. This also gives them more torque at lower rpm.

No kidding
By Argon18 on 4/3/2013 9:49:47 AM , Rating: 4
Of course Ford, Toyota, and Hyundai are going to poo-poo modern clean diesel engines which are superior in terms of torque and fuel efficiency. Of course they're going to say gasoline engines are "better" because that's the only thing they offer right now in the US. I'm sure those same marketing execs are running ad campaigns in Europe talking about how superior diesel engines are to gasoline! It's old fashioned regional market advertising.

These innovations that they claim have improved gasoline engines - turbocharging, direct injection, etc. all came from diesels. Diesels had it first, because diesels are ~10 years (or more) ahead of gasoline engines in terms of technology.

Variable geometry turbos appeared on diesels starting in the late 90's. It wasn't until 2010 that they appeared on gasoline cars, and even then it was only very high end cars (think 911 turbo).

Direct injection has been on diesels since 1989, while it's only just made it to gasoline in the past 3 years.

RE: No kidding
By lagomorpha on 4/3/2013 10:05:54 AM , Rating: 2
A lot of parts of diesel engines aren't perfectly analagous to equivalent parts of gasoline engines so it doesn't really make sense to say one is "x years ahead".

For example, if a gasoline engine is not direct injection it means the fuel injector is seperated from the cylinder by the valves whereas in a diesel engine that is not direct injection it means there is a prechamber into which fuel is injected attached to the cylinder but with no valve in between. It seems like a minor distinction, but very different things are happening for very different reasons.

You are right about the article being nonsense though. Even with modern technology the percentage of energy going to actually moving the vehicle is a lot better in diesels than gasoline engines particularly when pulling a load where diesels benefit from torque rise.

RE: No kidding
By Spuke on 4/3/2013 4:34:55 PM , Rating: 2
gasoline engines particularly when pulling a load where diesels benefit from torque rise.
So torque doesn't rise in a gasoline engine?

RE: No kidding
By lagomorpha on 4/4/2013 7:30:49 AM , Rating: 2
So torque doesn't rise in a gasoline engine?

Not as load increases.

By btc909 on 4/3/2013 1:38:57 PM , Rating: 3
How to beat Diesel fuel economy levels, get rid of Ethanol!

RE: Diesel
By PaFromFL on 4/3/2013 7:49:53 PM , Rating: 2
Very true! The handful of cars I've tested on long trips (> 500 miles) exhibited a 7% to 10% gas mileage reduction when running E10. This is much worse than the theoretical 3% loss based on energy density arguments.

I find this sketchy
By L1011 on 4/3/2013 11:56:29 AM , Rating: 2
I find the claim that gasoline engines/hybrids are catching up to diesel in torque to be sketchy. Fuel efficiency perhaps, but not torque.

I made a spreadsheet when I bought my Golf TDI and since I drive a lot of miles/yr (around 24,000) a diesel made great economic sense for me. Over the life of the car (200,000 miles) I expect to save nearly $8,000 in fuel when compared to my previous gas car. All said, I estimate about $3,500 in total savings for the life of the car.

My TDI is a BLAST to drive because of the torque. Like the old saying says: Horsepower is cool but Torque is your friend.

RE: I find this sketchy
By lagomorpha on 4/3/2013 12:06:04 PM , Rating: 2
I find the claim that gasoline engines/hybrids are catching up to diesel in torque to be sketchy.

That really depends on if you're talking about peak torque or area under the curve. Lies, damn lies, and statistics and all...

By talikarni on 4/5/2013 3:03:25 PM , Rating: 2
the cost of adding hybrid technology for the consumers about $1,500 compared to a cost of about $5,000 to add diesel power.

Uh say what? A $10,000 battery and $5,000 to 15,000 worth of additional electronics only costs the people $1500 more?

I know finding a single vehicle line that has diesel, gas, and hybrid technology is tough. But one such line is the 2013 VW Jetta.

Average prices within 200 miles of me (north FL):
Gas $25,000 ($23 to 30K depending on options)
Hybrid SEL $30,000 ($29 to 31K depending on options)
Diesel TDI $26,000 ($24 to 28K depending on options)

Looking at the fully loaded high end of all 3 variations, they all run around $31,000 at most. The base least number of option models range from $23K for gas, $24K for diesel, and $29K for hybrid (due to fewer "option variations" available on the hybrid line).

Average price shows that vehicles with Diesel engines is on par with gasoline vehicle prices, yet hybrids, even after a $1500 subsidy rebate from the government still averages quite a bit higher than the others.

Even in full size trucks (most of which do not have hybrid versions available), the only real reason for the $5,000 price increase for diesels is the higher end diesel engine (Cummins, Power Stroke, etc). The truck models that have a comparable smaller V8 or even inline 6 diesel engines run the same comparable price ranges to gasoline version as the Jetta shown above.

So really this guy was just making false claims to push their falsified "green" agenda.

RE: Cost
By arnold2 on 4/5/2013 3:29:25 PM , Rating: 2
Here in England we've been running common-rail injection diesels in passenger cars for about 10 years.

I've had 2 Diesel Ford Focus - but like a lot of drivers, I'm switching BACK to petrol - or more accurately hybrid Toyota.


Here are the bills you'll get running your diesel car anything over 3 years and 30,000 miles - from

And I have had ALL these problems in 2 cars - this is not some 'internet theory'!!

Dual mass flywheel failures on manuals leading to failures of drive, often incorrectly prescribed as clutch failure when in fact it is the dual mass flywheel that has failed: £800 - £1,500.

Turbo and intercooler failures: £1,000 - 1,500.

EGR failures: £300

Manifold swirl chamber failures: £300 +

Injection pump failures £1,000 - £2,000

Injector failures £250 - £1,500

Diesel particulate filter failures £500 - £1,500

Glowplug failures up to £1,000 if they come out. Up to £3,000 if they snap and the head has to be removed to extract them.

Cool weather performance?
By RobFromMooseJaw on 4/3/2013 1:34:40 PM , Rating: 2
Since October, people in my area (Saskatchewan, Canada) with diesel engines have been plugging their trucks in and only now, with the snow starting to melt, have most of them stopped plugging in. Even brand new diesel half tons going through their first winter were plugged in every night all winter long.

Few people with gasoline engines need to plug in at all any more because engines have improved and winters have warmed up so much since my childhood that we now only hit -30 (Celsius) a handful of times each winter. However, the idiots who bought diesel half tons start plugging in when zero-ish temperatures begin in October.

Perfect for Volt-like vehicles
By DT_Reader on 4/3/2013 3:21:20 PM , Rating: 2
There's a reason Diesel locomotives work the way they do: Diesel engine drives a generator, which powers electric motors which drive the wheels. This is essentially the Volt model, but the Volt uses a gasoline engine. Diesel's are far more efficient when run at an optimized RPM under variable load, as in a locomotive. Gasoline engines are not very good at fixed RPMs with variable load. The Volt would be much better off with a Diesel engine.

By paintit77 on 4/4/2013 6:58:32 PM , Rating: 2
I am sorry but this whole article is a lie. The new Ram 2500HD has a Cummins in line 6 diesel that has 865 foot pounds of torque at 1900 RPM. Nothing comes close to that in an engine burning gas. There is no comparison or chance in hell that Gasoline ever catches up to the efficiency of Diesel. It's physics. What has destroyed diesel in the US is the EPA and the Oil Companies as well as the IRS. First it is taxed higher per gallon by 19 cents. Why, because the Feds loose money on the highway tax due to farmers and constructions companies not paying taxes on the fuels. 2nd the EPA. President Bush's EPA destroyed Diesel in 2003 by requiring Exhaust recirculating and made the manufacturers install DEF to convert nitrogen oxide to nitrogen. It kills the efficiency. 3rd the Oil Companies tied the price of the fuel to Heating Olil demand. Hence raising the price of the fuel even further. It's great.

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