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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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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.


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