R-Squared Energy Blog

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Diesel or Gasoline?

I hear a lot of questions about the economics of a diesel engine versus a gasoline engine, given the fact that diesel prices are now much higher than gasoline (and likely to remain that way).

Diesels have two things going for them. First, a gallon of diesel contains more energy than a gallon of gasoline. Second, a diesel engine achieves a higher compression ratio, and gets more useful work out of the engine. Diesels are estimated to be around 30% more efficient than combustion engines.

I checked the EPA’s site on fuel efficiency – http://www.fueleconomy.gov – and compared a 2009 Volkswagen Jetta on diesel versus gasoline. Comparing identical cars – 2-L, 4-cylinder, 6-speed manual transmission shows that the diesel version gets 36% better fuel efficiency.

If I factor in diesel’s higher price – the EPA assumed $4.65 for diesel and $4.33 for premium gasoline – it costs $3.42 to drive 25 miles on diesel and $4.33 to drive 25 miles on gasoline. The annual fuel costs, assuming 15,000 miles of driving, was $2051 on diesel and $2598 on gasoline.

The diesel engine will set you back a few more thousand dollars than the gasoline engine. It is hard to get a direct comparison, but a search of Edmunds indicates that Volkswagen’s diesel models are at least $2,000 more expensive than comparable gasoline models. If we assume no time value for money, you are going to have to drive about 55,000 miles before you save $2,000 in fuel costs (based on today’s prices).

It just wouldn’t pay off for someone like me who doesn’t drive more than 5,000 miles a year. I am not even sure I drive enough miles to justify paying the extra cash for a Prius. I need to run those numbers next.

July 10, 2008 Posted by | fuel efficiency, Prius, Volkswagen | 41 Comments

70 MPG Volkswagen Golf Hybrid

Thanks to a reader for calling this story to my attention. I will be spending most of my time in the U.S. by summer, and I think I am going to have to get a car. Right now, I don’t own a car, and am happily biking to work. ๐Ÿ™‚ While biking is the national pastime in the Netherlands, I fear this is not a good option for Dallas.

The New VW Golf Diesel Hybrid

I had just about decided on a Toyota Prius – because it gives me the best possible compromise between something I can haul the family in, and something that gets great gas mileage (EPA-estimated 46 mpg). I really couldn’t find anything else that came close. (Suggestions are welcome, though).

But the Prius will soon have a worthy challenger. Volkswagen has announced that they are building a diesel hybrid Golf that gets 70 mpg. Wired reports:

According to a Google translation of Germany’s Auto Bild, the potential Prius killer sports a 74-horsepower three-cylinder TDI engine — Autoblog speculates it’s the 1.4-liter used in the Polo BlueMotion — mated to a 27-horsepower electric motor and a seven-speed double-clutch DSG transmission. There’s a nickel-metal hydride battery in the trunk; a regenerative braking system helps keep it charged. The car has stop/start capability and a full-electric mode at low speed. An “energy monitor” display on the dashboard keeps tabs on what the powertrain is doing.

According to Auto Bild, the hybrid Golf will get 69.9 mpg and emit 90 g/km of carbon dioxide. An earlier report by Britain’s Auto Express said 89 g/km, but either way that’s less than the 104 g/km emitted by the Prius and 116 emitted by the Honda Civic Hybrid.

When can I buy one? Well, there’s the rub. Reports are that they are expected to be on sale in Europe at the end of 2009, but no details of when it might be released in the U.S. (Although that link does say that it will meet California’s stringent air emissions standards).

Looks like I will just have to get that Prius, unless someone can suggest something better.

March 6, 2008 Posted by | fuel efficiency, hybrid, Prius, Toyota, Volkswagen | 273 Comments

70 MPG Volkswagen Golf Hybrid

Thanks to a reader for calling this story to my attention. I will be spending most of my time in the U.S. by summer, and I think I am going to have to get a car. Right now, I don’t own a car, and am happily biking to work. ๐Ÿ™‚ While biking is the national pastime in the Netherlands, I fear this is not a good option for Dallas.

The New VW Golf Diesel Hybrid

I had just about decided on a Toyota Prius – because it gives me the best possible compromise between something I can haul the family in, and something that gets great gas mileage (EPA-estimated 46 mpg). I really couldn’t find anything else that came close. (Suggestions are welcome, though).

But the Prius will soon have a worthy challenger. Volkswagen has announced that they are building a diesel hybrid Golf that gets 70 mpg. Wired reports:

According to a Google translation of Germany’s Auto Bild, the potential Prius killer sports a 74-horsepower three-cylinder TDI engine — Autoblog speculates it’s the 1.4-liter used in the Polo BlueMotion — mated to a 27-horsepower electric motor and a seven-speed double-clutch DSG transmission. There’s a nickel-metal hydride battery in the trunk; a regenerative braking system helps keep it charged. The car has stop/start capability and a full-electric mode at low speed. An “energy monitor” display on the dashboard keeps tabs on what the powertrain is doing.

According to Auto Bild, the hybrid Golf will get 69.9 mpg and emit 90 g/km of carbon dioxide. An earlier report by Britain’s Auto Express said 89 g/km, but either way that’s less than the 104 g/km emitted by the Prius and 116 emitted by the Honda Civic Hybrid.

When can I buy one? Well, there’s the rub. Reports are that they are expected to be on sale in Europe at the end of 2009, but no details of when it might be released in the U.S. (Although that link does say that it will meet California’s stringent air emissions standards).

Looks like I will just have to get that Prius, unless someone can suggest something better.

March 6, 2008 Posted by | fuel efficiency, hybrid, Prius, Toyota, Volkswagen | 78 Comments

70 MPG Volkswagen Golf Hybrid

Thanks to a reader for calling this story to my attention. I will be spending most of my time in the U.S. by summer, and I think I am going to have to get a car. Right now, I don’t own a car, and am happily biking to work. ๐Ÿ™‚ While biking is the national pastime in the Netherlands, I fear this is not a good option for Dallas.

The New VW Golf Diesel Hybrid

I had just about decided on a Toyota Prius – because it gives me the best possible compromise between something I can haul the family in, and something that gets great gas mileage (EPA-estimated 46 mpg). I really couldn’t find anything else that came close. (Suggestions are welcome, though).

But the Prius will soon have a worthy challenger. Volkswagen has announced that they are building a diesel hybrid Golf that gets 70 mpg. Wired reports:

According to a Google translation of Germany’s Auto Bild, the potential Prius killer sports a 74-horsepower three-cylinder TDI engine — Autoblog speculates it’s the 1.4-liter used in the Polo BlueMotion — mated to a 27-horsepower electric motor and a seven-speed double-clutch DSG transmission. There’s a nickel-metal hydride battery in the trunk; a regenerative braking system helps keep it charged. The car has stop/start capability and a full-electric mode at low speed. An “energy monitor” display on the dashboard keeps tabs on what the powertrain is doing.

According to Auto Bild, the hybrid Golf will get 69.9 mpg and emit 90 g/km of carbon dioxide. An earlier report by Britain’s Auto Express said 89 g/km, but either way that’s less than the 104 g/km emitted by the Prius and 116 emitted by the Honda Civic Hybrid.

When can I buy one? Well, there’s the rub. Reports are that they are expected to be on sale in Europe at the end of 2009, but no details of when it might be released in the U.S. (Although that link does say that it will meet California’s stringent air emissions standards).

Looks like I will just have to get that Prius, unless someone can suggest something better.

March 6, 2008 Posted by | fuel efficiency, hybrid, Prius, Toyota, Volkswagen | 39 Comments