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Automotive News & Views Has CAFE reached the end of its usefulness?
507 messages, Last post on Oct 27, 2009 at 11:49 AM
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Replying to: tpe (May 14, 2007 4:57 am) ?? time=distance/velocity time=(50 miles)/(90 mph) + (50 miles)/(10 mph) time=5.556 hours Average velocity = distance/time = (100 miles)/(5.556 hours) = 18 mph
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Replying to: tpe (May 14, 2007 4:57 am) I bought a new Suburban in June of 1998. It had a 1999 VIN. The dealer told me that Chevy had reached their quota on 1998 Suburbans and had to start selling them as 1999 models. This was to avoid paying CAFE fines. I think the market can best regulate the mileage of vehicles. As the gas prices slowly escalate people will look for higher mileage cars. There is no way I will ever own a 35 MPG gasoline car as my main transportation. None of them are what I want in comfort or safety. The only way to significantly cut our consumption is with diesel engines and to a lesser extent hybrids & EVs. The latter two require new battery advancements to be really practical. |
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Replying to: m6vx (May 14, 2007 7:16 am)
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Replying to: gagrice (May 12, 2007 7:08 pm) No, the efficiency (as measured by the rate of gals used per mile) in your example is the same.
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Replying to: li_sailor (May 14, 2007 9:02 am) For me I would rather have a car that gets 50 MPG at 75 MPH than one that only gets 50 MPG at 55 MPH. Where I live the highway traffic runs 75 MPH + most of the time. |
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Replying to: tpe (May 14, 2007 4:31 am) If I sold two cars and told you that they were both driven 1000 miles and their average fuel efficiency was 25 mpg you could not tell me how much total gas these cars burned. Now if I told you that they averaged .04 gallons per mile you could answer that question. Absolutely true….but we’re talking about an average of many thousands of cars in each "mpg-point", and they, on average, drive the same amount of miles, so this is not a factor. If the miles are the same, then both ways calculate the same amount of gas consumed. . If instead CAFE was .04 gallons per mile then if an auto manufacturer sold a 10 mpg vehicle he would now have to sell 4 40 mpg vehicles to be in compliance. But that’s because the average of .1 gpm (10 mpg) and .025 gpm (40 mpg) is 16 mpg, which is much lower than the mpg avg of 25. As I've already pointed out, the 2 averages are not equivalent, you cannot compare them directly. If instead CAFE was .04 gallons per mile then if an auto manufacturer sold a 10 mpg vehicle he would now have to sell 4 40 mpg vehicles to be in compliance. If "compliance" meant that they would have to average .04 gpm, you're right. But that would simply mean that the requirement was to have a sliding scale.
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If you told me that you had 100 miles to drive and asked how long it would take I could care less about your average miles per hour. Don't follow. If my avg speed for that 100 miles was 60 mph, I did it in 1:40. If you drove the first 50 miles at 90 mph and the next 50 miles at 10 mph then your average speed was 50 mph. As was pointed out, this erroneous. For CAFE to be anywhere near accurate it needs to use a weighted average, which is accomplished by the inverse method. One has nothing to do with the other. Anything can be weight-averaged. Funny you should mention it, since I work with Nielsen ratings, which one must weight-average (duration-weight in this case) to compare a 30 show with a 60 min show (for ex). The CAFE formula does, in fact work exactly this way, weight-averaging the mpg averages by number of vehicles sold at each mpg point. The way it stands right now people believe that if you doubled CAFE you would cut your fuel consumption in half. That's just not true. Well, actually, if mpg goes from 27 to 54, one's consumption is, indeed, cut in half. You could theoretically double CAFE and actually increase your fuel consumption if you did this by creating some ultra-high efficiency vehicles, say 70+ mpg. It would be great if they actually did that  Although true that different combinations could, in fact, be utilized, yielding varying overall consumption, the reality is that carmakers work under many constraints and wind up evening it out pretty much. This is the polarization of the fleet that I am referring to. This polarization, for the reason you suggest, doesn't exist...or if it does, it's pretty near impossible to prove. |
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I think the facts are this. No matter how CAFE sets their regulations the automakers will build what the people want to buy. If that were true, then CAFE would not have worked, and it most definitely did. It stopped 'working' long ago (since its points were reached) but that's another matter. The dealer told me that Chevy had reached their quota on 1998 Suburbans and had to start selling them as 1999 models. This was to avoid paying CAFE fines. Then what happened in 99? Funny then, that GM has never paid any CAFE fines. Nor Ford, nor Chrysler:Summary of CAFE Fines Paid I think the market can best regulate the mileage of vehicles. LOL. I guess that's why mpg has gotten worse, not better, since CAFE reached its numbers.
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Replying to: li_sailor (May 14, 2007 4:25 pm) As far as the 1999 Suburbans I asked that very question "what happens when you sell all the 1999 quota". He really did not know. When I bought it was the beginning of the 1998s GM strike. That may have had a bearing on it. The dealer in Sun Valley had pre-ordered a lot of them as it was his biggest seller. I was lucky to get one at all. Oh, and it served me well. I wish I still had it instead of this GMC Hybrid. No wonder MB cars cost so much. I'm sure they tack that fine on the price of the car. Now that Ford and GM trucks are mostly flex fuel they will get a bye on CAFE fines even with the new standards. CAFE is such a major rip-off on the American people. |
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Replying to: tpe (May 14, 2007 8:07 am) You're trying to hold distance constant as the Europeans do (eg 3L/100km). [volume/distance] In the US, we hold volume constant, how far on a given amount of fuel - miles/gallon. [distance/volume] So average mpg would average the amount of miles travelled for a gallon of gas. If you were to use gallons/100 miles travelled, then the average gallons/100 miles would be the average amount of fuel burned over a 100 mile distance. So for your argument to work, you have to stop using the term "average mpg".
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