MPG Illusion: cash-for-clunkers bill should use the 1 Gallon Per Mile principle
The cash for clunkers compromise that was reached in Congress this week puts a lot of focus, understandably, on the miles per gallon rating of the cars in question. It's understandable because MPG is how most Americans think about fuel consumption. But, as we've discussed in the past, gallons per mile is another useful metric, and its proponents have updated their site with an article on Cash for Clunkers and the 1 GPM Principle.
What's the 1 GPM Principle? Well, it's the idea that:
a new car needs to save 1 gallon of gas every 100 miles compared to the original car to be carbon neutral. The new car will then offset the CO2 emissions from its own production in 70,000 miles of driving, which would occur in 4 to 7 years for most drivers.Since the cash for clunkers proposal is designed to sell a lot of new cars and trucks, these vehicles will need to be built (well, there is a bit of a backlog available for now, granted), which will create more CO2. The CO2 emissions generated in the building process would be offset by the reduction in fuel use if the new cars are all at least 1 GPM (or should that be 1 GPHM?) better than the clunker that gets traded in. The trouble is that the way that the MPG requirements are set up in the compromise bill, specifically the markers for large light duty trucks, which only require improvements of one or two mpg, don't achieve carbon neutrality as written. A more approriate ruleset, the GPM propnents argue, would require vehicles that get 16 mpg or less to be replaced by a vehicle that gets 2 mpg better; 17-20 mpg vehilces would need to be swapped for something that's at least 4 mpg better; and anything that gets 21 mpg or better would need to be boosted by at least 6 mpg to get the vouchers. You can find the full details on the 1 GPM Principle here.
[Source: MPG Illusion via Green Car Reports]
Photo by KB35. Licensed under Creative Commons license 2.0.
Reader Comments (Page 1 of 1)
Phil L. 3:31PM (5/08/2009)
My frustration with all of this, no matter how they work the numbers: Yes, I drive older cars (which I maintain faithfully and try to minimize use), so the legislators think I'm paying close attention to their efforts.
But I'm not. My current life situation pretty much dictates any future vehicle shopping be restricted to the used market; all of the bills I've seen so far concentrate on new car purchases only. Some might look and me and swear I'd have no problem buying whatever is on the showroom floor. But the realities of raising kids, saving for retirement, and not using consumer credit keep me out of new car dealerships.
I'm sure I'm not the only one out there...
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wapiv 8:35PM (5/08/2009)
You're not the only one out there.
Jon 5:50AM (5/09/2009)
You hit the nail on the head. It is much cheaper to buy a used car than a new one with the discount. I saw this on the BBC this morning:
http://news.bbc.co.uk/1/hi/business/8041228.stm
lne937s 3:37PM (5/08/2009)
for an alternative calculation from Nissan:
http://www.nissan-global.com/EN/ENVIRONMENT/GREENPROGRAM_2010/CO2/index.html
If producing a car creates 3920 kton of CO2 and vehicle total lifecycle use consumes 147,000 kton, then you would need a ~3% improvement in efficiency to justify scrapping the old vehicle for a new one.
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Captain Morgan 3:46PM (5/08/2009)
Mr. Blanco has it wrong, as usual ... the cash-for-clunkers deal has nothing to do with improving efficiency. That's just a smokescreen. It's about economic stimulus ... it's about getting people into dealerships and spending money. Lawmakers saw how effective the pilot programs from other countries were at "selling new automobiles", and they wanted to mimic that result here. Environmentalism is just a marketing tool for what is ultimately another form of government handouts.
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GoodCheer 4:26PM (5/08/2009)
To be honest, I think I'd rather give $4000 handouts to consumers and let them pick which OEMs they like (and reduce fuel use as a bonus), than simply give low-interest loans to OEMs when they fail to attract enough buyers.
Duke Nukem 4:17PM (5/08/2009)
Who said cash-for-clunkers should be all about CO2 emmisions? If anything it's an economic stimulus package, with the added benefit of slightly reducing our dependence on foreign oil.
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greg 10:07PM (5/08/2009)
70,000 miles is assumed? Almost any car made today will last double that.
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Phil L. 10:27AM (5/09/2009)
Greg -
The 70,000 mile figure represents the "break even" point at which a new, more efficient car (based on their presumptions) will offset the CO2 from its own production. Clearly, the car must last much longer than that for there to be much of a new gain.
Phil L. 10:31AM (5/09/2009)
Aaargghh: "new" should be "net". C'mon ABG: Give us a short-term "edit" feature!
greg 10:38AM (5/09/2009)
If 70,000 miles is the break even point then anything beyond that should be a net gain, correct?
Chris Kaiser 5:50PM (6/02/2009)
I covered this story in my blog that cited the original author of MPG Illusion. I have a calculator that compares two different scenarios and shows why looking at GPM is better than MPG.
http://blog.mapawatt.com/2009/06/01/cash_for_clunkers/
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