Friday, December 10, 2010

More Cars Get 40 MPG; Ethanol on the Hill

A couple of Friday articles of interest:

Automakers are offering more conventional cars that cross the 40-miles-per-gallon threshold in highway driving, but relatively low gas prices continue to hold off buyers.
"When gas is cheap, no one is going to be rushing out to buy a small car," says Gabriel Shenhar, senior auto test engineer for Consumer Reports.

But automakers are keenly aware of how many were caught short in 2008 when gas prices shot up to a $4.14 per gallon peak in July, so they are adding 40-mpg cars as a hedge.
Two interesting tidbits (my italics):
In past years, few models were able to get a 40-mpg rating without using more expensive hybrid or diesel technology. Now automakers are starting to show they can hit that mark with improved conventional gasoline powertrains for a smaller price premium — or none.

"We found that 40 (mpg) is the new 30. Everyone wants great fuel mileage," Chevrolet spokeswoman Lesley Hettinger says.

Thursday, December 9, 2010

Fiji water is from Fiji

Fiji water comes in a beautiful bottle. 

I paid attention to the Fiji bottle for the first time when my wife bought one at the Atlanta airport while we waited for a connecting flight.  I was struck by the bottle.  The graphics and name evoked a serene feeling.  I thought it was a very nice job of marketing.  Someone made filtered water from somewhere nearby seem serene and exotic.  It wasn't until I took a close look at the bottle that I discovered Fiji water was in fact from Fiji.

This water had travelled from halfway around the world to be in Atlanta.  (I won't point out the obvious--it tasted a lot like North Carolina water...)

View Larger Map

Tuesday, December 7, 2010

Miles per Gallon Rating for the Home

The Earth Advantage Institute has developed a program for evaluating home energy use that they call the "Energy Performance Score" (EPS).  They refer to their evaluation system as an "“MPG” or miles-per-gallon style rating or label for the built environment."

On this page, they note that:
Why is it different?
Unlike other existing rating systems such as HERS (Home Energy Rating System), EPS enables home buyers to assess actual energy consumption between homes, rather than comparing energy efficiency levels that could be similar for both a large and a small home.
The contrast with HERS is an interesting one.  Two homes of different size are analogous to two cars with the same MPG that drive different distances. Valuing an upgrade depends on total energy consumption, not efficiency alone.  Energy consumption is a function both of efficiency and use (i.e., house size, miles driven).

Although the MPG metaphor is a catchy one, EAI is actually offering an assessment of energy consumption--which is the right thing to focus on.

Saturday, December 4, 2010

What 100 MPGs looks like in 2010

The Automotive X- Prize was launched in 2006-2007 to inspire the creation of the first safe, practical vehicle to achieve 100 miles per gallon. The prize: $10 million.

The prize was awarded earlier this Fall to 3 teams. (Follow this link to an NPR story.)

The Edison 2 (top right) achieved an MPG above 100 using an internal combustion engine. It took home $5 million. The Li-ion (middle right) is a hybrid. The X-tracer (bottom right) is battery powered.

Because vehicles can achieve their efficiency using different fuel sources, the competition relies on an MPG measure called "MPG equivalent," or MPGe. The denominator for MPGe is created by translating all energy sources used (gas, electricity, etc.) to the energy equivalent of burning a gallon of gas. MPGe has the virtue of allowing one to compare and then combine across energy sources. However, it inherits all the usual problems of MPG--an improvement from 10 to 11 MPGe saves the same amount of energy as the improvement from 50 to 100 MPGe for a given distance of driving. (Aside: A "gallons equivalent" per 100 miles would fix this illusion.) A second fundamental problem with MPGe is that, because it mixes energy sources into a single number, it obscures the cost and greenhouse gas emissions of different vehicles.

Fast Company wrote this about the Edison 2 (top right):
The highly aerodynamic vehicle has wind-shrouds over its tires and weighs a mere 840 pounds on the road, both of which help it with its phenomenal fuel efficiency (for comparison the top-selling, well-known and supposedly eco-friendly 2010 Toyota Prius manages just 50 MPG--half the VLC's ability).
We're particularly taken with the look of the thing. It's by no means conventional, nor is it approaching the sort of design and engineering requirements a real, sale-worthy road-going car would need (although it's got heating, ventilation and passed some of the tests required for a car to go on sale in the U.S.). But it looks extraordinary--much more attractive than the odd electric Aptera, with which it shares some design cues. And this, more than anything, helps it promote the notion of alternative power and alternative design in cars which might help more eco-friendly cars race onto the market.
These cars are not actually ready to be commercialized. As noted in the NPR story:

Supporting 60 MPG

If you are interested in supporting the 60 MPG target, take a look at this site run by the Union of Concerned Scientists, the Sierra Club, the Natural Resources Defense Council, and Environment America. Click on the icon:

Go60mpg Site Badge

Tuesday, November 23, 2010

Raising CAFE to 60 MPG

Earlier this fall, the Obama administration released a call for a 60 MPG standard by 2025. The announcement followed two other relevant news items.

First, two polls this year have asked about public support for stronger efficiency standards. This poll was released earlier this year by the Consumer Federation of America. A second poll by Mellman was released in September. This is my favorite result from the Mellman poll, "83% favor paying an additional $3,000 for a vehicle in 2025 if they would then save $3,000 in gasoline costs within four years of purchasing the vehicle."

Second, a report authored by John DeCicco at the University of Michigan shows that a 60+ MPG target is feasible by 2025 at the current rate of technological improvements. (Here's a brief summary.) A key assumption is that future technological improvements will be applied to efficiency rather than increases in horsepower.

Gregg Easterbrook wrote about the mpg/horsepower tradeoff two years ago in a post at espn, "Like weight, horsepower depresses fuel economy. Simply knocking a third off the horsepower of new U.S. passenger vehicles would, in about a decade -- as efficient new vehicles replace wasteful old ones -- eliminate approximately the amount of oil the United States imports from the Middle East. Yes, it's that simple."

Easterbrook noted that we'd spent two decades-plus diverting most technology improvements to horsepower while holding efficiency constant. To see this pattern, take a look at this graph from a recent paper by Soren Anderson, Ian Parry, James Sallee, and Carolyn Fischer:

This paper by Christopher Knittel at UC Davis explains the fundamental tradeoff between MPG and horsepower and how technology improvements have pushed out the "“fuel economy/weight/engine power production possibilities frontier” between 1980 and 2006. This picture captures the story:

The key argument in the DeCicco paper is that we do not need to sacrifice horsepower from where it is (after three decades of improvement) but simply redirect future technology improvements to efficiency while holding horsepower constant.

The governor's of eight states support the proposed increase in MPG standards. As noted on, "Nothing has been decided just yet, and we are not in a comment period. The 62 mpg level got a big pile of support from the governors of eight states – New York, Maine, Massachusetts, New Mexico, Maryland, Pennsylvania, Oregon and Washington – and other early voices are in favor of the go-big-or-go-home proposal. The governors write:
We urge you to set ambitious new standards for passenger vehicles. We have seen the automakers meet goals time and time again, and we are confident that technological improvements, including the plug-in hybrids and pure electric vehicles that they are rolling out, will increase efficiency and affordability further and will make 60 miles per gallon commonplace."

Tuesday, October 26, 2010

Fuel Consumption Standards for Heavy Trucks

[Update 10/28: A useful summary from]

Earlier in the year, the NRC released a report on how to reduce fuel consumption of large trucks (see here and here). Last week the EPA issues a first ever fuel efficiency standard for trucks--see stories at greenautoblog and at USA Today.

Here is a summary from the USA Today article:
"The complex proposal would cut fuel use 10% to 20%.

"We've been flatlined at 6 to 6.5 miles per gallon for years" for a loaded tractor-trailer rig, says Glen Kedzie, vice president at the American Trucking Associations, a major industry trade group. That translates to about 16 gallons of diesel fuel per 100 miles. A 20% gain would cut fuel use to about 14 gallons per 100 miles.

Major trucking and shipping interests endorsed the move for its potential cost savings.

ATA noted that it has backed fuel-consumption regulations since 2008. "The proposal, using current technology, is achievable," spokesman Brandon Borgna says.


Though the emphasis is on semi-tractor rigs and other big trucks, the regulations would apply to vehicles as small as those with an 8,500-pound gross vehicle weight rating (the safe weight of the truck and cargo combined) — a Ford F-250 pickup or equivalent.


The government forecast the truck rules would cost the industry $7.7 billion, but save $35 billion in fuel."

This is an example of "low hanging fruit" that pays for itself. We have noted in previous posts that improving the efficiency of trucks leads to a huge benefit because seemingly small MPG gains on inefficient vehicles saves the most gas. The next two graphs show the consumption over 10,000 miles of driving of the lowest MPG vehicles:

The top graph shows how steep the region is in the low MPGs (and how flat at high MPGs). The graph below focuses on the slope at the low end.

A vehicle that gets 5 MPG is using 2,000 gallons to drive 10,000 miles. Improve it to 8 MPG, and you save 750 gallons.

In the past, Rep. Sensenbrenner of Wisconsin has called for investing in improvements in truck technology. In 2009 he introduced a bill called the Heavy Duty Hybrid Vehicle Research, Development, and Demonstration Act, H.R. 445. Here is a recap of the legislation from September 2009:

The House also approved by voice vote H.R. 445, Heavy Duty Hybrid Vehicle Research, Development, and Demonstration Act of 2009, authored by Rep. F. James Sensenbrenner, Jr., a Wisconsin Republican.

The legislation directs the Secretary of Energy to establish a competitive research, development, demonstration, and commercial application program to provide between three and seven grants of up to $3 million per year each to carry out projects to advance research and development and to demonstrate technologies, including plug-in hybrid technology, for advanced heavy duty hybrid vehicles.

"I applaud the House for taking this important step in promoting new technology that will help achieve energy independence and combat climate change," Sensenbrenner said. "This legislation takes an innovative approach to reducing greenhouse gas emissions, lessening our dependence on foreign oil and strengthening the U.S. economy."

Sensenbrenner said he hopes that Senator Herb Kohl, a Wisconsin Democrat who is an original bill co-sponsor, will move the legislation through the Senate with similar success.

"The heavy truck sector accounts for approximately one-fourth of the nation's fuel use and the majority of transportation-based emissions," said Gordon. "Even small improvements in their efficiency can have a substantial impact."

"Hybrid technologies hold the promise of greatly reducing the fuel consumed by the nation's truck fleet," said Gordon. "This bill represents another common sense approach to chipping away at our energy challenge."

Tuesday, August 31, 2010

New EPA Labels Include Gallons per 100 Miles

The EPA is exploring the idea of requiring a "graded" fuel economy label for cars starting in 2012.

See the graded and ungraded versions here:

If you have any thoughts, you can leave comments at the bottom of the page.

We are happy to note that labels for gas engines include a "gallons per 100 miles" measure.

Read a full explanation behind the new label ideas here, including a description of the need for "gallons per 100 miles".

Sunday, July 25, 2010

Recent Reactions to the National Academy of Sciences Report

Here are a few reactions to the recent National Academy of Sciences Report on different options for reducing automobile fuel consumption--and the specific proposal to focus on fuel consumption rather than MPG when assessing improvements:

John Voelcker at Green Car Reports, who wrote this provocatively titled post in March 2009, weighs in on the report here and here. Voelcker writes:

More than a year ago, we wrote an article pointing out the flaws in the U.S. practice of measuring a car's gasoline use with the familiar miles-per-gallon (MPG) measure. Now, no less a body than the august National Research Council has agreed with us. As it noted in a pre-publication summary released by the National Academy of Sciences: Fuel economy data cause consumers to undervalue small increases (1-4 mpg) in fuel economy for vehicles in the 15-30 mpg range.


As well as the MPG recommendation, the report concluded that a combination of existing technologies could meet the now-enacted increases in corporate average fuel economy (CAFE). But it also noted that making cars more fuel-efficient would raise their cost, and that the payback for such measures depended entirely on the future price of gasoline.

Voelcker also says this about his original March 2009 post on MPG: "And if you still don't believe us, read the entire original article--which caused, ummmm, quite a lot of controversy when we first published it, and continues to generate readership and interest." We thank Mr. Voelcker for his willingness to stir the pot and live with the consequences.

Discovery News picked up Voelcker's post and summarized the fuel consumption argument.

Bengt Halvorson at The Car Connection summarizes the NAS report here. His reaction to the fuel consumption proposal:

The panel also reiterated what we at The Car Connection and our colleagues at Green Car Reports have argued in the past: that the information should, be displayed to consumers in terms of fuel consumption (amount of fuel used per hundred miles, for instance) as well as traditional miles per gallon. Most of the rest of the world shops for vehicles based on consumption, as it relates directly to fuel costs (and CO2 emissions).
And Thom Cannell and Allene Stark at the Autochannel's Detroit Bureau provide an industry perspective on the report, noting that the "investigators talked to all the key players; suppliers, car makers, and governmental units. They took things apart to understand costs, they made informed guesses when no one would divulge proprietary plans." Their main conclusion is that near term fuel savings must come from improvements on vehicles with conventional gasoline engines. The article provides a useful summary of the feasibility of different technologies.

Cannell and Stark summarize the argument for fuel consumption over MPG:

We need to shift to a different way of thinking about fuel consumption. Our familiar MPG must be replaced by gallons per mile or at least appear on the window sticker. Why? GPM (we think that it should be GPM/100 miles as in Europe’s L/100km) more accurately depicts your out-of-pocket costs, or what you pay for what you get. Think it’s crazy? Which of these is a better deal: making a car that gets 50 amazing mpg instead of only 35 mpg, or a truck that gets a paltry 20 mpg instead of 10? At only 10,000 miles per year driven, the car saves 86 mpg [sic--should read "gallons"] and the truck — wait for it - 500 gallons! If you drive 20,000 miles per year the later will save you about $3,000.

Monday, June 14, 2010

Interesting Items

A few reports and articles on fuel economy have come out recently that might be of interest:

1) Jon Krosnick, a Stanford political psychologist and survey methodologist, summarizes recent surveys on attitudes toward climate change, efficiency, and efficiency costs in this New York Times Op-Ed column (The Climate Majority).

One pattern of findings: "Large majorities opposed taxes on electricity (78 percent) and gasoline (72 percent) to reduce consumption. But 84 percent favored the federal government offering tax breaks to encourage utilities to make more electricity from water, wind and solar power."

Electric utilities often find that when they offer customers the option of buying "green" energy at a premium, few people are willing to pay the premium. Using a tax break to subsidize lower prices on green energy could encourage greater participation.

2) A survey from the Consumer Federation of America finds that Americans greatly overestimate the oil reserves under US control. The mean response was 40%. The CFA reports that the true number is 3%.

In an interesting twist, the surveyors then randomly assigned half the participants to learning the true value of US reserves (3%) before asking the question:

"The federal government has recently required automobile manufacturers to increase the fuel economy of their motor vehicle fleets from an average of 25 miles per gallon to 35 miles per gallon by 2016. Do you think the government should increase this standard to an average of 50 miles per gallon by 2025?"
Understanding the true level of US reserves increased support for a 50 MPG standard from 65% to 73%.

Here's the full survey summary.

3) The National Academy of Sciences is releasing a long-awaited report on how to improve fuel economy. The full report can be read here. One of the first issues addressed in the report is the need to use a measure of gas consumption instead of MPG. The NAS summary (linked to this Truth about Cars review of the report) states:
"Fuel economy is a measure of how far a vehicle will travel with a gallon of fuel, whereas fuel consumption is the amount of fuel consumed in driving a given distance. Although each is simply the inverse of the other, fuel consumption is the fundamental metric by which to judge absolute improvements in fuel efficiency, because what is important is gallons of fuel saved in the vehicle fleet. The amount of fuel saved directly relates not only to dollars saved on fuel purchases but also to quantities of carbon dioxide emissions avoided. Fuel economy data cause consumers to undervalue small increases (1-4 mpg) in fuel economy for vehicles in the 15-30 mpg range, where large decreases in fuel consumption can be realized with small increases in fuel economy. The percent decrease in fuel consumption is approximately equal to the percent increase in fuel economy for values less than 10 percent (for example, a 9.1 percent decrease in fuel consumption equals a 10 percent increase in fuel economy), but the differences increase progressively: for example, a 33.3 percent decrease in fuel consumption equals a 50 percent increase in fuel economy.

Recommendation: Because differences in the fuel consumption of vehicles relate directly to fuel savings, the labeling on new cars and light-duty trucks should include information on the gallons of fuel consumed per 100 miles traveled in addition to the already-supplied data on fuel economy so that consumers can become familiar with fuel consumption as a fundamental metric for calculating fuel savings."
The report relies on fuel consumption as its main metric when evaluating improvements--this is critical because it evaluates improvements to vehicles that range from trucks on the low end (that get 3 MPG) to hybrid technologies that achieve 100 MPG. Calculating the fuel savings from new technologies is easy with fuel consumption but confusing, at best, with MPG. For example, improving a truck's MPG from 3 to 4 saves 8 times as much gas over the same distance of driving as improving a hybrid car's MPG from 50 to 100.

We have written before about the benefits of small MPG improvements on trucks. (See these posts at Green Car Congress, Next100, and Fast Company article.)

As an extension of focusing on fuel consumption, the report focuses on percentage decrease in fuel consumption (FC) in place of percentage increase in fuel economy (FE):

Finding 2-2. The relationship between the percent improvement in fuel economy (FE) and the percent reduction in fuel consumption (FC) is nonlinear, e.g., a 10 percent increase in FE (miles per gallon) corresponds to a 9.1 percent decrease in FC, whereas a 100 percent increase in FE corresponds to a 50 percent decrease in FC. This leads to widespread consumer confusion as to the fuel-savings potential of the various technologies, especially at low absolute values of FE.
Here's our formula for converting from MPG% to GPM%

A pdf or hard copy of the report costs some money, but you can read it online for free. Here's the free NAS summary.

4) The Obama administration has issued a memo directing "the government to set the first-ever mileage and pollution limits for big trucks".

The University of Michigan has a useful summary

Section 1 of the "Presidential Memorandum Regarding Fuel Efficiency Standards" requests that the EPA and the National Highway Traffic Safety Administration immediately begin work on a joint rule-making under the Clean Air Act and the Energy Independence and Security Act of 2007 to establish fuel efficiency and greenhouse gas emissions standards for commercial medium- and heavy-duty vehicles beginning with model year 2014, with the aim of issuing a final rule by July 30, 2011.

This marks the first time that large commercial trucks will have to meet national fuel economy targets. In Section 1, the president specifically requests that the EPA and DOT consider the recommendations of the NAS report, as well as to take into account the market structure of the trucking industry and the unique demands of heavy-duty vehicle applications; job creation within the industry; and applicable state standards.

Wednesday, April 21, 2010

GPM bill passes New York State Senate

A bill sponsored by State Senator Daniel Squadron passed the New York State Senate last night by a 35 to 26 vote. It was part of a larger Earth Day legislation package.

The bill requires New York car dealers to post a chart converting MPG to gallons per 1,000 miles in 5 MPG increments (from 10 MPG to 50 MPG). Here is a copy of the bill.

Senator Squadron effectively argued for GPM as helping both consumers and the environment: It helps consumers recognize gas savings and it helps those concerned with the environment to reduce their environmental impact.

The opposition argued that GPM provides the same information as MPG (with a little more math) and that it puts New York car dealers at a competitive disadvantage and discourages car sales. How it is both redundant and harmful at the same time is quite a mystery!

(As we've argued, GPM is not redundant with MPG. Gas consumption is a highly non-linear function of MPG: The improvement from 15 to 20 MPG saves more gas over a given distance of driving than the improvement from 30 to 50 MPG. Will GPM discourage car purchases? No. It will call attention to the value of buying more efficient cars that save gas (and money and CO2), so it is likely to shift purchases from less efficient to more efficient cars. Will it make NY dealers less competitive? I can't see how GPM will lead car buyers to purchase otherwise identical cars in Connecticut rather than New York.)

The bill goes to the New York Assembly next.

The floor debate occurs around the 1:55 to 2:15 mark in this video.

Tuesday, February 23, 2010

Airplane MPG

In November, there was a nice post on R-Squared Energy Blog about airplane fuel efficiency.

Robert Rapier writes: "Often when I am flying, I think about the amount of fuel that the airplane is burning. Then when I am off the plane, I usually forget about it. I have heard mixed opinions on the overall efficiency of airline travel versus automobile travel, but just never got around to investigating the matter myself....."

After reviewing a bit of math he concludes that his per capita fuel economy on a recent 757 flight was 81 miles per gallon.

And then he notes, "Of course it is important to note that while the fuel economy looks pretty good, the miles traveled are very high relative to automotive transportation. I generally travel less than 5,000 miles per year with my car, so if I drive a car that gets 25 miles per gallon it would only take about 16,000 miles on an airplane to equate to an entire year's consumption in my car."

When comparing airplane and car fuel efficiency, there are a couple of allures of flying:

First, the MPG of flying is better than any car. But as Robert Rapier notes, many people fly much further than they drive. One could easily sweat the details of a car purchase--trading in a 30 MPG car for a Prius--to be green, but emit the equivalent annual CO2 savings on two round trip flights from the east coast to the west coast.

I created these graphs a couple of years ago to get a better appreciation of how distance and MPG tradeoff.
(The maximum MPG in these graphs is 50.)

The second allure of flying is that the plane was going to fl;y anyway so my marginal CO2 contribution is zero. But this calculation ignores the cumulative effect of individual demand. Higher demand in period t leads to more scheduled flights in t+1. It is an interesting social dilemma where each individual can feel like he or she is flying for free, but the plane wouldn't be flying if there were no passengers. Somewhere between the average CO2 contribution and the marginal CO2 contribution is the "true value".

Thursday, February 18, 2010

MPG, VW, and Honey Bees

An NPR story this week celebrated the incredible "fuel efficiency" of honey bees. They compared the energy efficiency of bee flight to a new VW vehicle called the L1.

The VW will purportedly get 170 miles per gallon.

The bee? 4,704,280 MILES PER GALLON!

What if we could magically convert the new VW to bee-level efficiency? How valuable would that be in gas savings? Let's look at gas consumption measured as gallons per 10,000 miles:

The VW L1= 58.823 gallons per 10,000 miles

The bee = .002 gallons per 10,000 miles
Replacing the VW with a bee would save 58 gallons over 10,000 miles.

Let's put this amount of gas savings in perspective. This same gas savings is achieved by the following trade ins (also over 10,000 miles of driving):

A 12 MPG vehicle for a 13 MPG vehicle
A 20 MPG vehicle for a 23 MPG vehicle
A 30 MPG vehicle for a 36 MPG vehicle

Here's another way to look at it:

The VW is about 7 times more efficient than an average car today that gets about 25 mpg. The bee is 200,000 times more efficient than today's average car! The efficiency of the bee seems to dwarf the efficiency of the VW.

And here's another way to look at it:

The ratio of the VW to the bee is miniscule. 170 MPG is less than .01% of 5 million MPG. It seems like nothing.

But let's put the 170 MPG in perspective. MPG misleads in this regard because it is gas consumption, not mileage, that matters.

If you drive today's average car 10,000 mile, you will use about 400 gallons of gas.

The VW will use 59 gallons of gas over the same distance. This saves roughly 340 gallons compared to today's car.

And the bee will use just 2/thousandths of a gallon and saves close to 400 gallons compared to today's car.

Surprisingly, although the VW MPG is less than .01% of the bee MPG, the VW MPG achieves 85% of the gas savings from Bee-level efficiency.

This is a lesson in why national policy needs to focus on gas consumption, not mileage: The important gas savings come from improving the efficiency of low MPG vehicles (e.g., trade ins of 14 MPG cars for 25 or 30 MPG cars). Replacing a 14 MPG car with a 27 MPG car saves more gas than replacing a 33 MPG car with a bee! Large MPG improvements on efficient cars do little to reduce gas consumption. Measures such as "gallons per 10,000 miles" makes this distinction clear.

Let's beware the obsession with large MPG numbers. Let's focus on improving low MPG vehicles.

Monday, February 8, 2010

Why GPM -- A Brief Review

Autobloggreen has a post on the New York State Senate bill that would require car dealers to describe fuel efficiency as "gallons per 1,000 miles". The post has prompted the familiar call for using the metric system (see this post on the connection between "GPM" and the metric system) and the familiar lament that people should understand the math.

A comment by "Throwback" on Autobloggreen reads:

Throwback 2:40PM (2/08/2010)

Another wasteful bill. What is the purpose? You don't think people understand that if they buy a car that gets 25 mpg vs 20 mpg they will be using less fuel? As a native New Yorker I am embarrassed by the (lack of) quality of the states politicians.

Here's a short answer to Throwback:

Yes, higher MPG is better than lower MPG, and people recognize this.

But people use the difference in MPG as the rough approximation of gas savings, which is misleading--often in a big way. Instead of subtracting MPG, car buyers need to first divide a given distance by each car's MPG, and then subtract. (See the last half of this post on the math.) That's what GPM does without effort--a standardized GPM measure can be subtracted to know actual gas savings.

Consider two trade ins:

A) 30 MPG to 45 MPG
B) 15 MPG to 20 MPG

Impressed by the 15 MPG improvement in option A? (A 50% improvement in MPG.)

Unimpressed by the 5 MPG improvement in option B? (A 33% improvement in MPG.)

Option A saves 11 gallons per 1000 miles; Option B saves 17 gallons per 1000 miles.

The New York bill is designed to highlight the gas savings available to people who are driving or considering cars in the teens. This is where the biggest savings are possible.

In fact, GPM may be most effective at keeping people who are currently driving more efficient cars from opting for less efficient ones. MPG tempts us to think that there is little harm in trading in a 20 MPG minivan for a 15 MPG SUV. What's 5 MPG? GPM makes clear the impact.

Compare MPG to "Gallons per 1000 miles" below:

MPG Gallons per 1000 miles
10 100
11 91
12 83
13 77
14 71
15 67
16 63
17 59
18 56
19 53
20 50
21 48
22 45
23 43
24 42
25 40
26 38
27 37
28 36
29 34
30 33
31 32
32 31
33 30
34 29
35 29
36 28
37 27
38 26
39 26
40 25
41 24
42 24
43 23
44 23
45 22
46 22
47 21
48 21
49 20
50 20

Friday, February 5, 2010

Gallons per Mile Bill Clears New York Senate Committee

[Update April 21: The GPM bill passed the New York Senate yesterday as part of larger Earth Day legislative package. See this post for details. The original bill, described below, required that dealers provide "gallons per 1,000 miles" for each vehicle they sold. The new bill requires that dealership display a chart translating mpg to "gallon per 1,000 miles".]

The New York Senate Environmental Conservation Committee has passed a new fuel efficiency bill that includes a "gallons per mile" requirement. The bill requires that vehicle manufacturers list "gallons per 1,000 miles" for city, highway, and combined driving.

The bill was championed by Senator Daniel Squadron, who laid out his rationale in this December article, and received broad support from environmental groups:
"Urging the passage of Senator Squadron’s bill were the New York League of Conservation Voters, the Environmental Defense Fund, the Natural Resources Defense Council, the Sierra Club’s Atlantic Chapter, and Senator Antoine Thompson, the Chair of the Environmental Conservation Committee."
The blog All over Albany lays out the case in more detail.

We believe this low cost change for presenting fuel efficiency information is of great value to consumers and the environment. We applaud Senator Squadron for endorsing it.

Although we advocated for "gallons per 100 miles" and "gallons per 10,000 miles" as useful standards in the supplement to the Science article, we note the benefits of "gallons per 1,000 miles":
  1. 1,000 miles is roughly what the average American drives in a month, so it is a meaningful number
  2. It allows easy estimation of yearly consumption (multiply by 10, roughly)
  3. It avoids the problem of seemingly small differences in efficiency that occurs when comparing "gallons per 100 miles"
Barry Nalebuff and Ian Ayres made the case for gallon per 1,000 miles in this Why Not? column for Forbes magazine.

Here is an excerpt from the bill (the full bill can be found here):


An act to amend the environmental conservation law, in relation to requiring automobile dealers display a fuel economy label on all new vehicles

To require that new passenger motor vehicles sold in New York State post a "gallons-per-mile fuel impact statement."

Adds a new section 19-1104 to the environmental conservation law to require vehicle manufacturers to display a gallons per thousand miles fuel impact statement. Such statement shall set forth the average number of gallons the vehicle is expected to use when traveling a distance of one thousand miles of city mileage, highway mileage and combined city and highway mileage. The bill provides for a civil fine of not more than $100 per vehicle to be imposed on manufacturers for a violation of this section.

Gallons per miles driven is a much more useful means of measuring fuel efficiency than the current miles per gallon standard. It enables a vehicle purchaser to more easily compare the fuel efficiency between various models of automobiles. This bill, which would require manufacturers to display the average gallons per one thousand city, highway and combined miles, will allow consumers to know accurately at a glance the cost of operating a vehicle over one thousand miles. Additionally, this allows environmentally conscious consumers to identify the relative environmental effect of different vehicles. Encouraging consumers to buy more fuel efficient vehicles can help save money, reduce greenhouse gas emissions, improve energy security and oil dependence costs, and increase energy sustainability.

The MPG Illusion among Transportation Professionals

Are transportation experts immune to the MPG Illusion?

In a presentation at the 2010 Transportation Research Board Conference entitled Mile-per-Gallon Illusions and CAFE Distortions: When Even Transport Experts Have Trouble, Dana Rowan, Alex Karner, and Debbie Niemeier of UC Davis report that transportation professionals make better judgments of fuel efficiency gains using "gallons per 100 miles" than using MPG.