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Automotive News & Views How The 35 mpg Law By 2020 Will Affect The Cars We Will Drive
538 messages, Last post on Jul 31, 2008 at 6:28 AM
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One of the 'peculiarities' of the CAFE system is that in computing the averages it uses the harmonic mean as the methodology. Here's the wiki reference..CAFE wiki "Fleet fuel economy is calculated using a harmonic mean, which results in slightly different values than simple averaging.[2"
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the most recent year I have read numbers for is 2005, when Ford was the only one of the biggies to miss the truck standard, by like 0.1 mpg. But they are all at right around the 22.0 mark today, and that is including Toyota. And considering they are using smaller car-based models as "trucks" for CAFE purposes, that's really extremely underwhelming. RAV4s, Outbacks, and PT Cruisers all count as "trucks" for this purpose. But then. that's old news. Did the truck loophole go away with the new CAFE bill the Prez is about to sign? I heard they had done away with it, but I don't know specifics. Anyone? |
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Replying to: kdhspyder (Dec 17, 2007 1:10 pm) Example: 1) a 35 mpg vehicle uses 2.86 gal / 100 mi driven 2) a 25 mpg vehicle uses 4.00 gal / 100 mi driven If another vehicle is to be added to balance out the 25 mpg vehicle ( 4 gal used per 100 mi ) it has to be a vehicle that only uses 1.72 gal per 100 miles driven. Why? The two vehicles together must average 2.86 gal / 100 mi ( 5.72 gal / 100 mi together ). Thus if one vehicle uses 4.00 gal then the other must only use 1.72 gal. This is a very accurate and rigorous mathematical application of the idea of 'averages'. The result is that to balance out a 25 mpg vehicle that uses 4.00 gal to drive 100 mi a manufacturer must also sell a 58 mpg vehicle ( 1.72 gal / 100 mi ). Thus the key factors then are... ..two vehicles together must only use 5.72 gal each to go 100 mi. ..three vehicles together must only use 8.58 gal each to go 100 mi. ..four different vehicles, 11.44 gal to go 100 mi each. It would behoove the manufacturers not to have too many vehicles at 25 mpg or lower ( CAFE testing procedures ). For every 30 mpg vehicle, a 42 mpg vehicle is required in order to balance out at 35 mpg. OTOH if a vehicle maker has 2 vehicles getting 58 mpg ( 2 x 1.72 ) then a third vehicle can as low as 19.5 mpg.
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Replying to: kdhspyder (Dec 17, 2007 2:17 pm)
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Replying to: blufz1 (Dec 17, 2007 9:42 pm) Then they, along with VW, have to educate the American public on the benefits and savings of diesels. Then they have to achieve very good fuel economy. I think after the emissions are taken into account as well as our heavier vehicle weights here they should easily get about 40 mpg which is fantastic. But then they somehow have to convert their entire fleet, which is not so certain - at least not right away. But yes since they don't have any heavy vehicles they should be the first to reach the 35 mpg average out of all the vehicle makers. The Ridgeline, Odyssey, MDX, Pilot and Accord all as diesels will put them easily at the new CAFE levels. |
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the problem of filter traps and longevity standards. I am a big diesel fan but realize my choices escape scrutiny because 3/4 ton vehicles have a commercial rating and don't have to meet car standards. If they did in California then the trouble free smog equipment standard comes into play. Nippon might have the real numbers but I believe the standard is something like 60 or 100k miles without servicing. If a particulant filter has to be replaced or serviced in 20 or 30K the rules would have to change and the manufacturer would have to pick up the whole cost of the servicing. At least that is how I used to believe the standard was prior to the 2002 ban on new diesels in our state. At that time only VW was grand fathered in and of course heavy duty diesels. It will be interesting to see if the new diesels offered in cars will meet the current gas standards. I can promise you this, the diesels I saw in London in 2006 didn't meet the sight and smell test of this one Californian. But they may have been older diesels.
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Replying to: boaz47 (Dec 18, 2007 10:36 am) 100K miles, boaz. They want to extend it to 150K miles, basically the serviceable life of the vehicle, so they won't have so many poorly tuned, poorly maintained cars running around not meeting smog standards. 150K miles is already the required warranty for emissions performance for all cars sold as AT-PZEV (a California-only standard). And BTW, Californians have that 100K mile rule to thank for not having to smog check their new cars for the first five years of ownership. 
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"WASHINGTON (AP) - Congress by a wide margin approved the first increase in automobile fuel economy in 32 years Tuesday, and President Bush has signaled he will accept the mandates on the auto industry." Congress Requires Better Car, SUV Mileage |
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Replying to: nippononly (Dec 18, 2007 1:25 pm) From what I have read to meet our standards for air quality they have had to install filter traps in the low sulphur diesels and those traps required service at 20 or 30K. Would that have to be addressed for California? All 3/4 diesels require now is a visual inspection to make sure you still have a diesel. some people were buying old diesels and replacing them with new gas engines to avoid the required smog check.
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Replying to: 1stpik (Dec 15, 2007 7:10 pm) "Better" is a relative term. While there may be more efficent powerplants available, the saving grace of the IC is the inexpensiveness of the powerplant AND its fuel. This inexpensive quality has allowed cars to become widespread. |
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