Quote:
Originally Posted by MetroMPG
I'm glad you said "energy" impact. Do we also compare the energy content of diesel fuel vs. gasoline in evaluating their merits? A gasoline powered vehicle getting the same MPG as a diesel is significantly more energy efficient.
I find these discussions often tend to end up in the realm of "how many angels can dance on the head of a pin?"
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Yes, I think that would certainly be fair game for consideration. And also how diesel requires far less energy to refine, including the nasty chemical manipulation and alteration necessary for gasoline. Or, using my car as an example, how the diesel engine is epa rated at 44 mpg while the 2.0L gas is rated at 29 mpg. (52% better mileage with 12% more btu's per gal. Before the EPA decided to lie about average diesel fuel economy, the stickers showed a 58% advantage for the diesel engine.) You simply cannot argue the logic of diesel engine efficiency superiority. Direct Injected gasoline engines may start to blur the lines a little bit.... which is awesome.
Of course, ymmv. Certainly kudos are due to those of you pulling down stellar mileage figures with gasoline. And I don't disagree that a hybrid is still a better choice for all city driving. But when I see a prius rocket along at 80+mph on the highway I cringe a little bit. Happens a lot in southeast MI.
Not really feeling you on the angel pin thought...?
edit; just found a different source citing more like an 18% btu advantage for diesel... numbers seem to be all over the place. Also interesting to note might be that those running pure biodiesel are actually at a lower btu level / gal than regular unleaded gasoline.