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Automotive News & Views MPG Ratings Will Drop Under EPA Proposal
375 messages, Last post on Oct 02, 2008 at 9:08 PM
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See this Edmunds.com article! EPA Overhauls Fuel Economy Estimates for 2008 - As the 2008 model-year cars hit the lot, shoppers will notice a big difference — the EPA has changed its fuel economy testing methods to produce mileage estimates that reflect "real world" driving habits. - (more)
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Replying to: larsb (Sep 29, 2008 4:27 am) the only cng vehicle for sale i know of is the civc gx. go down to the local dealer and try to buy one. |
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Replying to: mattandi (Sep 29, 2008 10:26 am) Not really, it's complicated because they calculate fuel used based on carbon in the emissions. A complicated formula does not mean that the the concept has to be complicated. The concept for determining fuel use is a mass balance on carbon. The carbon in the exhaust comes from the carbon in the fuel and the fuel contains a certain percentage carbon, from all this you can determine the amount of fuel that was used. In essence it is weight per mile that is then converted to distance per gallon. Not sure why you think that is a problem. Once the weight of fuel per mile is determined, you would just take the inverse and multiply by the density of the fuel.
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Replying to: jeffyscott (Oct 01, 2008 6:12 pm) Not sure why you think that is a problem. Well, it's just a conflict that occurs when the test protocols, procedures, and estimates run into reality. The tests and resulting estimates are intended to provide consumers with a means to compare different cars. That is all well and good until the consumer actually buys a car. Then those tests and estimates are transformed in the new owner's mind into a prediction of the MPG they will actually get with their new car. Not at all what the government intends. When there is a difference, and there almost invariably is a difference, the owner concludes that the EPA test sucks and the EPA testers are idiots. Now the test doesn't suck and the testers are not idiots. Just a misunderstanding, or mistaken assumption, of what the test actually tells us. There is only passing resemblance between the test and reality. You and I don't drive on a dynamometer. We drive on streets. We don't control and repeatedly test the fuel we put in our cars. We buy what the local station has available. We don't give weight to the various components that make up the fuel and figure that into our actual MPG. We choose regular or premium and maybe try to avoid ethanol. We don't have precision instruments connected to our cars picking up minute bits of info as we drive them around. We have a fuel gauge and an odometer. We don't follow a carefully controlled set of protocols and driving sequences. We sit in traffic jams while we take the kids to dance class. We don't measure emission from our exhaust and extrapolate the data to a class of cars for comparison. We fill up our tank and wonder what the price will be the next time we need to fill up. Carefully controlled tests and consistent results and calculated estimates run into the chaotic and uncontrolled reality of fickle, irrational, unpredictable, and emotional drivers. Not sure I would characterize it as a problem really. It is what it is. There just is no way that test can possibly tell us what so many of us want that test to tell us. |
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Well it got porked up. Every Senator with a pet amendment figured this is a must do bill, so why not tack on a tax break or two. I am sure we all agree that a tax break to rum producers in Puerto Rico will solve the credit crisis. Anyway, amongst the fat is an interesting tidbit, Transportation and Domestic Fuel Security Provisions. Included a tax credit for plug-in electric drive vehicles, like the Chevy Volt. Minimum $2500 plus $417 for each kWh battery capacity above 4 kWh. Limits set by weight. Most passenger vehicles will probably get the $7500 limit on vehicles with a GVWR of 10,000 pounds. Limit is higher for larger vehicles. |
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