Miles per gallon? or Miles per Dollar? a better way to measure fuel efficiency?
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We've talked here before on numerous occasions about how the average fuel efficiency of new cars and trucks hasn't really changed much since the late 1980s. We've also discussed the fact that simply mandating that car makers produce more efficient vehicles is not enough when fuel prices are low enough that drivers aren't yet willing to give up their bigger more powerful vehicles. Since American politicians clearly don't have the political backbone to drive up the cost fuel through tax policy, another approach is clearly required.
In a recent editorial piece, writer Lawrence Ulrich proposed a simple measure that might help drive home the cost of driving to American consumers. Since the efficiency of most cars doesn't change radically over time and many people pay for fuel at the pump with credit card rather than cash, they tend to be somewhat less aware of what's happening. However if instead of using the relatively static metric of how many miles you get from each gallon of fuel, you switched evaluating the miles you can go on a dollar's worth of fuel, a lot more volatility would be apparent. By dividing the MPG by the unit cost of fuel to get miles per dollar, you would get a live measurement of efficiency that more closely tracks cost. It's an intriguing idea, although it's not clear how practical it is. For it to be useful people would actually have to do the calculation each time they fill the tank. Or else in vehicle displays of mpg would need a way to input the dollar cost each time you got a fill-up (in-car computers that can calculate these numbers on the fly do exist, at least in test vehicles). Chime with you thoughts on this one and ideas of how to make it work.
[Source: MSN Autos, thanks to JJ for the tip]
Reader Comments (Page 1 of 1)
jcwinnie 10:26AM (2/07/2008)
Good old Sam, if there is an opportunity for his green transportation blog to ignore GHG emissions from automobiles, he will certainly exercise it.
$ Dollars comprise a good measurement of economic impact
mJ Megajoules comprise a measurement of efficiency and are a better unit measure than gallons or liters, which is biased toward ICE
CO2e (CO@ equivalents) comprise a measurement of emissions, which need to be drastically reduced. When all should, how many cars sold in America actually meet the basic upper limit of 120 gms CO2e per kilometer suggested by the European Commission?
So it should be an index, Sam, miles per all three.
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Throwback 10:30AM (2/07/2008)
Let's be honest Sam, how many Americans are demanding our politicians raise the gas tax? Any politician that voted for such an increase would be defeated in their next election, if not recalled before that.
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Whopper 10:44AM (2/07/2008)
Sam, I tried your $/mile gauge over the life of two Chevy pickup trucks I owned. I used initial purchase price, operating cost (fuel, maintenance, insurance, license etc), depreciation and trade-in value at the end. Both trucks were 2wd, V6, manual transmission, full sized trucks and averaged 20 mpg. Bottom line cost per mile, when adjusted for inflation, was $0.78 per mile in todays $. Cost of fuel was minor compared to purchase price, depreciation, insurance and maintenance.
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Nick 10:34AM (2/07/2008)
I think they should measure efficiency by greenhouses gases released per mile. And they should include the production of the car in these statistics (as well as regular maintenance, such as brakes, or replacing the batteries on a hybrid).
For example, they can make an assumption about X tons of CO2 used to make the car, the hybrids, batteries, etc and amortize them over the expected life of the car or the component (such as batteries, brakes, oil, etc).
This way we have an ACTUAL greenhouse gas estimate on efficiency.
Because, lets face it, replacing a 20-yr old car that gets 30 mpg with a new hybrid that gets 35-40mpg doesn't reduce greenhouse gases for a long time, because of the amount of CO2 required to produce a brand new car.
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rgseidl 10:35AM (2/07/2008)
Consumers are quite aware of gas prices already. They usually know how much they paid for their last fill-up. Also, the new EPA08 fuel economy stickers already indicate annual fuel cost based on a somewhat realistic estimate of cost per gallon and annual mileage. However, car makers can only influence MPG directly, so that is what is used for CAFE and the gas guzzler tax (still measured according to the old EPA rules, though).
MP$ is most useful when estimating the total cost of ownership (TCO) of different drivetrain options, e.g. conventional gasoline vs. flex-fuel vs. hybrid vs. T2B5 diesel vs. CNG etc. This calculation takes into account new vehicle purchase price, license fees & taxes, insurance, consumables, depreciation as well as fuel cost for an assumed annual mileage. Commercial fleet operators routinely base their purchasing decisions on TCO considerations and so do well-informed private buyers.
For example, every year ADAC in Germany produces a major TCO study covering gasoline and diesel variants of roughly 780 new vehicle models offered in that market. The full report is available at a fee, so here is the summary of the 10 models for which the 2007/2008 diesel version is cheaper to own - in terms of Euro cents per km driven in the first four years - than the comparable gasoline one. Unsurprisingly, the difference is most pronounced for premium models and SUVs.
http://www.adac.de/images/b-d-vgl-auszug_tcm8-131259.pdf
Note that these results for Germany cannot be applied directly to the US or any other market, as virtually all inputs and assumptions are different! The idea is merely to illustrate the concept of a TCO calculation.
In Europe, where fuel is much more expensive than in the US, fuel cost still only accounts for ~20% of TCO. Asset depreciation is actually a much more significant factor.
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Karkus 11:02AM (2/07/2008)
jcwinnie
Most people care about $, not about GHG, when how they buy their cars (OK they also care about image, mostly). Sam was just throwing out another idea to get people to realize how much they're spending, so that maybe they indirectly also reduce GHG. I don't think it would work well because gas prices change all the time. Also, the window sticker already has an estimated yearly fuel cost on it.
No need to get down on Sam on this...he was just throwing out another idea. He's one of the best bloggers here, and unlike some of the other bloggers on ABG, his post are usually accurate, relelvant , and show some insight into the car industry.
The answer to you question is 2 cars. The Civic Hybrid and Prius.
http://www.vcacarfueldata.org.uk/information/how-to-use-the-data-tables.asp#petrol
Also, The 120 g/km is NOT an upper limit.. it would be the average. Also, 120 is a POSSIBLE future regulation - it may be 125 or 130, not be adopted at all.
Nick,
Your thoughts about a new car requiring lots of CO2 are wrong and are too simplistic. You assume that if you buy a new car, the old one gets thrown away. Wrong. Someone else will drive it until it dies.
So someone has to buy new cars. Period.
So, it's better for you to buy a fuel efficient new car , than for someone else to buy a regular car. Because that way YOU determine what's going to be on the used car market in a few years, and you show the carmakers that people want more fuel efficient cars. If YOU just buy used cars, you're letting other people determine the cars that get put out on the road.
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Zigster 11:15AM (2/07/2008)
People don't factor inflation into their calculations - they think $1 gasoline in the '70's was cheap. Gas is expensive but not quite off the charts historically. There is not that much to drive home, yet.
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Tim 11:15AM (2/07/2008)
How about a ratio of cost/Co2 per mile taking into account the ENTIRE energy cycle INCLUDING taxpayer subsidies such as direct payments to producers, Taxpayer subsidized R&D, Direct payments to foreign governments, WAR (direct and cost including military and collateral damage pain & suffering of lives lost on BOTH sides) and Nation Building to secure supply including funding HUNDREDS of military bases worldwide to "protect" democracy etc.
Of course, there is the indirect cost of the rest of the world HATING the US because we FORCE them to accept "democracy" so that we can be "free" the way we tell them to be free (or at so we can have access to their markets including oil). You’ll eat your spinach and you’ll like it… or else we’ll pay you to eat it or maybe torture you until you comply!
We are the Americans. You will be assimilated. RESISTANCE IS FUTILE!
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Ralph 12:07PM (2/07/2008)
From a consumer's point of view, a more relevant calculation is cents per mile where you include the cost of depreciation, maintenance and fuel into the mix. One of the problems with electric cars in the past (in addition to range) was that even if the fuel is cheap, lead acid batteries have to be replaced every few years to the tune of $2000 to $3000 dollars and this made pure electrics unattractive as a financial proposition. If rechargeable batteries cost $3000 and lasted 10 years, then you're more likely to see electric cars adopted. Cents per mile including maintenance, depreciation and fuel is the best way to look at car ownership for the consumer.
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GreyFlcn 12:37PM (2/07/2008)
Gallons-per-Mile is a more accurate measure of fuel economy.
Or as the Europeans do it Liters-per-100-Kilometers.
http://gristmill.grist.org/story/2007/12/19/152610/35
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Bill 2:25PM (2/07/2008)
Miles/Week is my measure of choice. Drive less!
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Paul Allen 6:03PM (2/07/2008)
The fueleconomy.gov site has an interesting addition to their standard ratings:
Fuel cost to drive 25 miles.
Presenting economy this way really makes you realize the difference between vehicles in a real world sense, in my case
My Audi S4, $5.16
Wife's Acura MDX $4.85
Kid's Sonata V6 $3.34
Versus, say:
Civic Hybrid $1.92
Prius $1.67
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jj 1:56PM (2/07/2008)
Miles per dollar is an excellent idea because with alternative fuel costs it'll be easier to compare since we won't be changing our currency. How do you compare EVs, Hydrogen cars, to compressed air cars with gas price when the one common denominator is dollars?
Take for example when a gallon of gas was a $1 to $3 dollars now. If you get 20mpg, before you'd get 20 miles-per-dollar, now you only get a poultry 6.67 miles-per-dollar. Now you can compare on equal grounds if you took Tesla's converted 135mpg at $3 gas price it'll be 45 miles per dollar. Prius is something like 15 MPD.
But the difference is for Tesla, electricity prices would have to go up to decrease mileage because it's not affected by gas prices. So you can continually compare on equal cost grounds.
Most of all this calculation is based on how much you spend for how much you travel because it's on the per-dollar.
Per-gallon focuses on your car's efficiency mileage for the gallon of gas. MPG doesn't show price fluctuations in fuel prices that surely will be the case this year when gas hits 4 dollars.
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hektik 5:27PM (2/07/2008)
Hi there,
My tiny SEAT Arosa 1.7SDI, eight years old, uses less than 6 litres to do 100 km, mostly urban.
My wife's TOYOTA Corolla 4D4, averages 4.5 litres every 100 km in a road/motorway/urban cycle.
My next, and expected, car will be a LOREMO LS, which is said to return 100 km every two (2) litres. As practical as my current Arosa, but one third as thirsty.
I care about emissions, and I do care about my purse.
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Alex 9:21AM (2/08/2008)
i prefer to look at total cost of ownership. i drive a 1992 nissan maxima. i get around 20 mpg. that's not very good... at all. However, i have not made a payment on that car in 11 years. no major repairs so far either. so if i did get a new car with better mileage, i would be loosing money. i see no reason to replace the maxima until repair bills exceed a new loan payment.
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Clague 4:55PM (4/17/2008)
MP$ is a better way in that it gives you your costs for comparing with different grades of gas or diesel. BMW'S and other luxury cars require premium fuel. Also a Mercedes diesel may get you 30+ mpg but the price difference between diesel and gas is like getting 24 mpg in a gas engine. Diesel used to be cheaper than gas (many moons ago) and recently was the same as premium gas but now runs about .40 more than premium.
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Kevin Price 4:37AM (4/24/2008)
i would like to know where to buy a natural gas car? where to fill up the car in the state of utah in particular? how much the cars go for? how many miles to the gallon they get? and what is the price per gallon of natural gas to fill up your car in utah?
thanks,
Kevin
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Kevin Price 4:39AM (4/24/2008)
i would like to know where to buy a natural gas car? where to fill upthe car in the state of utah in particular? how much the cars go for?how many miles to the gallon they get? and what is the price pergallon of natural gas to fill up your car in utah?thanks,Kevin
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Devin Serpa 7:02PM (9/16/2008)
I love the idea, check out http://www.afteroilev.com/mp$_metric.php for a calculator of MP$
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