Emissions Standards - "Good For Fuel Efficiency," Consumption Data Says
This is probably going to rub people the wrong way.... I've listened to plenty of people claim that emissions standards are choking fuel efficiency... But not once did anyone bring any data to the table....
First, a time line (cite: http://www.epa.gov/reg5oair/mobile/history.htm) Quote:
1970-1975 - first emissions standards 1977-1988 - tightened emissions standards 1990-1994 - tier I emissions standards 1999 - tier II emissions standards Now, fuel consumption over time. http://primitiveengineering.com/fe/c...gervehicle.JPG Notice the huge drops in consumption beginning with the first fuel emissions standard. In 1999, the slight upward trend was reversed - I'm not so sure I'd call that significant, but the change in emissions went from .6gpm NOx to .3 gpm NOx (compared the difference to the 1975-1981 -- 3.1gpm to 1.0). There's not enough data to say what the trend is after 2004.... But what about fuel efficiency - the mpg numbers you ask? Unfortunately, the BTS only has new car mpg data starting in 1980... But, for all cars on the road, data goes back to 1960 (which just means effects lag behind in year)... So, for all cars on the road http://primitiveengineering.com/fe/milespergallon.JPG Again, mpg numbers go up immediatly following the emissions standard being put into place... But, after 1990 (tier I) - things stay flat. Feel free to poke holes - but, if you're going to do so... you sure as hell better back it up with reliable data. My data is coming from the BTS http://www.bts.gov/publications/nati...on_statistics/ - so I'm expecting source quality to at least match that :D I put the effort in, I'm expecting you to do the same ;) And one more thing... I couldn't care less about your anecdotal evidence ;) Bring data^http://upload.wikimedia.org/math/1/a...e08521cced.png |
Are emissions and CAFE the same thing? There were several changes during those time frame.
Also how do we know that without emissions that the MPG would not also increase. We have no data because the it's illegal to do so but there have been folks that pull emission stuff to get better mileage or run leaner getting higher NOX levels that would not meet the EPA standards but get better FE. |
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One of the things I wanted to bring to the table is that emissions standards doesn't automatically mean lower fuel economy. That is, fuel economy and emissions can coexist. For example, Tier II emissions went into place - and we didn't see any significant change in FE or total consumption. Additionally, if we think of emissions equipment as a hindrance... Every car has the same requirement to meet - but there's still an increase in the mpg numbers and a decrease in consumption (the mfr's were still able to decrease consumption with the standards in place). What I'd like to know, if I had a time machine, if these standards weren't put in place - would we see the same upwards trends in fuel efficiency? EDIT: To answer your question... No emissions and CAFE are independent. I've got the data for mpg versus CAFE standards somewhere, I'll look for it. |
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For the Impala... someone posted in another thread... Quote:
94-96: 4221lb 00-05: 3465lb So the weight in 1958 is almost the same as 2005.... This could be isolated, but it strikes my interest strings :D But ya, there's a lot missing (I totally agree)... I've got some other points, but If I post it all - I'm worried no one will say anything at all (I'm looking for different perspectives). Impala info http://www.goissca.org/imp_hist.htm |
Fuel efficiency should should follow CO & HC reductions. NOx is the one that is fought at the expense of efficiency.
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What you said is true - for a case by case comparison... But step back and look from the designer perspective (the person being told to make it more fuel efficient AND put out less NOx), not the end user. |
Its taking a narrow view of the situation assuming all your FE gains are due to more efficient combustion. The aerodynamic improvements are absolutely huge. Everything has an OD tranny now. Tires and oil are leaps and bounds ahead. The catalytic converter has to be one of the best devices ever invented. Advances in manufacturing methods and materials deserve great credit, they had the potential to design great cars in the past but couldn’t mass produce them cheap.
To get some perspective though, a 55 chevy could get 25 mpg and its every bit the car as todays midsizes when comparing room and cargo capacity. |
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It's almost foolish to say emissions standards are causing fuel efficiency to go down - when, in reality, fuel efficiency has gone up or (at least) remained flat. |
Well it is both true and false.
Diesel particulate filters require fuel to function so all diesels this year burn more fuel than last year to be cleaner. Fighting NOx is costing us MPG as well. But you are right that we are getting cleaner every year and FE is holding for the most part. Like I said earlier though, most of the basic tech and theory was available a long time ago, its largely more implemented now though because we have better manufacturing tools to implement it. edit: I forgot to add as well, changes in fuel formulation have also had a big effect on the cleanliness of cars, and that’s really an external to the idea you are putting forward. |
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