You save more fuel switching from a 15 to 18 mpg car than switching from a 50 to 100 mpg car.
Okay, I’m obsessing. But apropos of my post yesterday on how SUVs can save the climate, I just calculated this little fact and I had to share. This assumes, of course, that both cars are driven an equal amount. (Hat tip is in order for Jon Rynn, commenter at Gristmill.)
So, we should stop trying to design a techno-magic, futuristic “super-efficient car.” It really won’t end our oil addiction or save us from climate change. That’s right: no more HyperCar and no more FreedomCar. At least not until we’ve done the dull and unsexy work of boosting fuel economy at the bottom of the fleet, where it matters far, far, far more.
The real fix for oil addiction isn’t exciting, and it doesn’t lend itself to massive research investments. But the good news is: we just need to do stuff that we already know how to do. So here’s my new policy proposal. While CAFE standards (fleet averages) are groovy, what we really need to do is simply outlaw vehicles that get below, say, 15 or 18 mpg.
It’s easy like that.
Check out the chart below the jump…
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I realize that this is wildly counterintuitive, but it’s true. The explanation is here.
See the raw numbers and check my math here (Excel spreadsheet). It’s much simpler than you probably think.
For fuel economy, the numbers DO lie
Sightline’s climate policy project
that’s just amazing! and the math even checks out! Geez, it might be dull and unsexy, but it sure spun my head around…
Eric, you’re right that our habit of thinking in miles per gallon is a mental obstacle to appreciating where the big savings can come from. I’m wondering if a bar-graph version wouldn’t be more effective than a curve. Then one could more easily eyeball the comparative effects.For fun, I’ll add that switching from a 15mpg vehicle to one that gets 22mpg is about equal to no longer driving the 50mpg vehicle. This thread also reminds me of the McKinsey chart that’s going around (p xiii). The report identifies car hybridization as the most costly (“that’s smug, Bart”) method to address CO2e emissions with a small potential for tonnage reduction, while improvements to fuel economy in light trucks could save us money (under current cost regimes) and lead to significant tonnage reductions.
Eric de Place
bahouse,Great points. Say, it turns out that’s suprisingly hard to communicate this stuff—people just don’t believe it! (At least not until they see the numbers and chart.) So if you’ve got any ideas about how to communicate, I’m all ears.The bar-graph version might help, you’re right. I’m also working on a gallons-per-hundred-miles version that I think is clearer in some ways.
There is also a third factor at work here which you cannot ignore. To show the true picutre, the 2-D graph that you have produced should actually be a 3-D graph, with the third axis being the number of vehicles at each millage rating.Depending on the distribution of millage across the entire U.S. automotive fleet, a small change in a medium-millage vehicle, which is driven by a large majority of people, may have a greater impact overall than an enormous savings in a small percentage of the fleet.Of course, all of this hinges on getting good data for the distribution of fuel efficiency across the nation.
Quite right, Igallop- the chart here by itself shows absolutely nothing. How many miles are driven by the very-low-efficiency vehicles compared to medium efficiency ones? And what ratio would justify the title “18 is enough”? (Enough for what, exactly?) And whence the false choice between making the different classes of cars more efficient in the first place- why not do both? I fail to see how the very basic insight presented here changes anybody’s thinking on the issue.
Eric de Place
lgallop,You’re absolutely right that the distribution of vehicles across the spectrum of mpg rating matters a lot from the perspective of macro fuel savings. In fact, depending upon how things are distributed, CAFE standards can be pretty unhelpful. In some scenarios, it’s better to set minimum performance standards than it is to just set an average and let individual vehicles get any old rating so long as they average out. If I get my hands on some reliable distribution data I may try doing a post on this.
Eric de Place
gh74, I think you’re misunderstanding lgallop’s point. The chart shows that it’s far more important to get the least efficient vehicles off the road than it is to invent radically new efficient vehicles. Same is true for vehicle miles traveled: reducing driving in the least efficient vehicles is WAY more important than reducing driving in medium and high efficiency ones. There’s no false choice: we can make 100 mpg vehicles and we can make SUVs more efficient. We should do both! (And we should reduce driving too.) But when we have to allocate our political or technical resources, then we should choose to work on SUVs because that’s where the big fuel savings are. Incidentally, last night I calculated that you save more fuel going from a 13 to 17 mpg car than from a 50 to 500 mpg car. I can’t speak for others, but that sure as heck changes my thinking on the issue!
Eric, I think you’re *ignoring* Igallop’s point, and mine. Your chart would show what you think it shows ONLY IF there are a large enough fraction of gas-guzzling vehicles on the road. This may indeed be the case, but it would be nice to have this information. If the 15 mpg vehicles only accounted for 1% of cars on the road (to pick an extreme case, clearly this is not actually true), would you still say it would be “enough” to go after this part of the problem? (And again, what exactly did you mean by “enough”?)I’m glad you agree about the “false choice”; I’m curious how you reconcile that view with your statement: “we should stop trying to design a techno-magic car for the future”. Or with your last statement of the original post. Sounds to me like you’re exhorting us to buy into said false choice.Anyway, if you had just framed the question as one of priorities, I would have (largely) agreed with you. I think you overplayed your hand when you started making statements to the effect that doing X will be “enough” to solve our problems. That statement (and it’s in your title!) assumes a ridiculous number of unknowns and feeds into our cherished mentality that curbing emissions will be easy and best shouldered by others.
Eric de Place
gh74, Oh, I think see what you’re driving at! Couple of points:1. I meant “18 Is Enough” as in “18 is the lowest fuel economy we should accept.” That’s why I recommend outlawing vehicles that are less efficient. I certainly didn’t mean: hey, 18 mpg is good enough.2. As I said earlier, I agree that the distribution matters. But the curve tells us that—no matter what the distribution of vehicles is along the mpg spectrum—the biggest savings will tend to come from those at the lowest end. From a fuel-saving perspective, it’d be wiser to concentrate on low-efficiency vehicles than on designing for the extreme upper end. That the difference betwen 50 and 500 mpg is smaller than the difference between 13 and 17 mpg should be some prima facie evidence of my weighting of the priorities.
Gov’t could more simply mandate fleet averages without setting a minimum MPG: namely target fleet average gallon / mile rather than mile / gallon! The following calculations show what would happen if the government mandated .0286 gallons / miles (the reciprocal of 35).So if say Ajax Cars, Inc. sold only 2 cars a year of equal popularity, and one car achieved 25 mpg ( 0.040 gallons/mile), their second car would need to achieve 58.3 mpg (.017 gallons/mile) to achieve a fleet average of .0286 gallons/mile. Notice that 58.3 exceeds 35 by 23.3, whereas 25 is short of 35 by only 10!
This is a great point, but you should know that the CAFE rules already take this into account!The CAFE standards aren’t a simple average, but are computed by “by taking the reciprocal of the arithmetic mean of the reciprocals” (from here). This is just a mathmatical way of incorporating the point you make in your post.In practical terms, it means that it’s much easier for auto makers to meet CAFE standards by raising the milage of the least efficient vehicles.It’s just like eliotc suggests: the CAFE standards are actually in terms of the more sensible gallons/mile, but, for whatever reason, we commonly talk about efficiency in gallons/mile.
Tomr, you have a very interesting point I didn’t know (not did Eric evidently)! And so it sounds like the CAFE standards, by regulating the reciprocal of mpg, already create an incentive for improving more on the low end mpg car rather than the “techo-magic” car of the future. So CAFE as written already addresses Eric de Place’s concern!That said, it makes economic sense for government research dollars to focus on fundamental Research & Development (R) only, not incremental R which the capitalist sector excels at. So let the Federal Gov’t to fund R into radical energy savings for cars, while the car companies’ research departments focus more on short term incremental improvements, because the latter responds both to the incentives of the free market and hitting the CAFE standard in the near term. Since in the long run, we want to achieve much much GREATER than 35 MPG …its reciprocal really 😀 … we eventually will need to “techo-magic” cars in the future, so basic research should start now.
This is an excellent endorsement of the way Europeans specify milea… er, fuel economy. They do it in fuel volume per distance, instead of distance per fuel volume.Here,15mpg = 15.68 liters per 100km18mpg = 13.06 lp100km50mpg = 4.71 lp100km100mpg = 2.35 lp100kmSo the equivalent statement is “You save more by switching from a 15.68 lp100km car to a 13.06lp100km car than you do by switching from a 4.71 lp100km car to a 2.35 lp100km car”. Stated this way, it’s pretty obvious.The only time distance per fuel volume is really good is in figuring out how far you can go before you run out of gas.The point about averaging the reciprocals is illustrated if one “averages” a 50 mpg car and a 100 mpg car: the average of 50mpg and 100mpg is 75mpg. But the same vehicles, 2.35lp100km and 4.71 lp100km average to 3.53 lp100km—or 67 mpg. So which is the meaningful “average”? I claim it’s the latter. And so, apparently, do the writers of the CAFE standards.You can do the same calculation while sticking with creaky old English units: 1/100 gallon per mile averaged with 1/50 gallon per mile is 3/200 gallon per mile, or 67 mpg.
an SUV using a gallon every 15 miles, would use 48 gallons for a 720 mile journey. I normally drive a SMART car.. over 60MPG, which would use 12 Gallons for the same journey.. and if you get SUVs to produce 60MPG, then at the same time, the smaller cars will get more efficient by adopting the same technology. The target (as a %) will always have a moving baseline. 18MPG would have still use 40 gallonsSo.. do you save 8 gallons switching to an 18 MPG SUV or 36 gallons by switching to a SMART car? (or other similarly efficient vehicles)..
And wouldn’t promoting both ends be the best of both worlds, knowing that there is a finite supply?
I would say that improving standards from the bottom up is fundamentally better because you are removing cars with low mpg instead of creating cars with high mpg. Thus, you are essentially making the car pool smaller and as supply goes down, prices go up. Economics will get people to think harder about other modes of transportation. Combine that with this math and its like killing two birds with one stone. A much better approach than the current one.
A great chart that emphasizes the need to get rid of lowest mpg transport. However a couple points seem to be missing:1) NECESSARY BUT NOT SUFFICIENTGetting to 18 is needed by not enough. Neither is a fleet average of 50mpg. Or even 100mpg. Climate change is going to force the entire vehicle fleet to be at least 500mpg within 3 decades. Anything less, including the Prius of today will not be drivable.There is no sustainable scenario that allows cars to burn fossil fuels much longer. The IPCC says 1 tonne per person in 40 years. But that 1 tonne will be much more needed for agriculture, construction, transport and other essentials that don’t have other alternatives. So by 30 years out we need near-zero-emission vehicles for the entire fleet. The vehicle fleet takes a long time to turn over. Many of the cars being sold in 10 years will be drivable in 30. With climate change you have to work *backwards* from future known limits…not forwards from today based on what seems “doable”.The chart needs a time dimension. An extention of the x-axis out to point where cars need to be in 30 years. Without this firm target it is hard to make any statements about what is “enough”Climate change requires a “techno-magic car for the future” and soon. Without it, few if anyone will be driving in 30 years. Nobody will be driving even a 50 mpg car by then. 2) ZERO THE X-AXIS I certainly agree that we should “simply outlaw vehicles that get below, say, 15 or 18 mpg”. But there are modes of transport that get far worse mileage than even the 10mpg of your charts x-axis minimum. It would be helpful to the general transport discussion to at least get to the 2 to 5 mpg range on the chart. That is the emissions-equivalent of a family of four flying.If we are going to outlaw choosing an 18 mpg transport choice, surely we should be outlawing choosing a 5 mpg transport choice as well.Climate change demands we look at the sustainable/survivable future and work backwards.
We keep talking about mpg without recognizing Javan’s Paradox. Using a resource more efficiently does not reduce overall consumption of that resource. It merely makes the consumption of that resource more valuable because it is so efficient.I have no doubt that 100% of the oil produced will be consumed in some form or another. 100% of the produced oil will enter the atmosphere at some point in the consumption chain. It will either be as jet fuel, diesel or gasoline somewhere on the planet. Doing so more efficiently in the western world only permits cheaper consumption of oil products in developing countries.We need to completely get off the casual oil consumption route. Electric vehicles are the only way to go. Air travel via jet needs to be drastically reduced or eliminated. Our electric grid needs to be 100% nuclear, solar, wind, etc.Otherwise, we can kiss it all goodbye.Forget about moving the SUV from 15 mpg to 18 mpg. We need to simply set a phase out period on gasoline for the average driver.
Eric de Place
morrison_jay,Your point about Javan’s Paradox is exactly right. Thanks for mentioning it. It’s another big reason by super-efficient future cars aren’t the end game. Personally, I don’t think we need to ban gasoline or air travel so long as we set a firm and enforceable carbon cap that corresponds to the best science for climate stabilization. We’ll need substantial carbon cuts across the economy—and transportation is huge—but as to where those cuts happen, I’m agnostic. Just so long as they happen.
Eric,I take a slightly diffent POV from these observations on MPG. The super efficient future vehicle is the end game, despite Javan’s Paradox. But it requires going electric for 99% of us. Electric scooters (i.e. Vectrix) or electric cars. I plan on buying the Aptera vehicle as soon as it is available in 2008 or 2009. I plan on getting a Vectrix electric scooter this spring.It is impossible to reconfigure housing for the entire nation. We have already built it. So some form of zero emmission transportation vehicle in necessary. The only way to go is electric. And we have to focus on phasing coal out of the mix of electricity.I don’t see any other realistic solutions. People are not going to willingly change their lives. So we have to look at the macro level. Focus on the electric grid, high carbon taxes and a lot of investment in battery technology, solar, wind, etc.
Eric, as a follow-up to your communications question on 12/23, I wrote the following news headlines. Maybe, they will stir an idea for you, maybe not.Samaria, 14th Century B.C.Shortly after escaping Great Flood, Noah’s Ark is engulfed by Great Hurricane. To save the Ark from sinking and the lives of all those on board, Noah invents utilitarianism to decide which animals to jettison first. Several specie of dinosaur, the wooly mammoth and the giant sloth vanish from gene pool.Rome, 42 A.D. Hoping to improve his failing public image and the national budget, Emperor Claudius declares all Christians must loose weight. Each must reduce his weight by 1 stone every year for the rest of his natural life. Those unable to loose the necessary weight must pay to the emperor bronze tribute equal in weight to their shortfall or face the lions. Beverly Hills, 1996.Richard Simmons announces a nationwide weight-loss contest. Contestants will have their starting weight measured on Day 1. At the end of each month, contestants will be awarded $1,000 dollars for every 1 percent of body weight lost. The competition will last for one year.
I think the question that should really be asked is, do we still want a car based culture in 10 years, 20 years, 30 years. And before that we really need to ask what would the planet look like? What will our psyches look like? Technologies cannot be pried from cultural circumstancce and is it possible (or desirable) to have the cultural mechanisms (the same ones that are killing the planet) and have “green” cars (even though that is impossible)a 500mpg car does not promote local communities. How much of this focus on cars is because cars are compatible with a healthy planet and community and how much is it due to the fact that the dominant culture, and those in are are addicted to cars and advanced technology?What would the world look like with out cars? What would the world look like without the internet or computers or televison? What would communities look like? feel like? smell like? sound like?
forestsareyourfriends, at some point we as environmentalists needs to propose realistic solutions as opposed to simplistic idealism.”a 500mpg car does not promote local communities.”Light rail or public buses do not promote local communities either. But on the same side, a 500 mpg car or light rail or bus system do not prevent local communities. They are not connected issues. It is a non-issue. Poverty does not promote local communities. If we destroy all jobs, that will promote poverty and misery. It will also lead to high crime and fear.We need to stay on topic. Let’s face it, with out current infrastructure, which is too late to demolish and replace 100%, this requires individual transportation (ie cars). So if we have to have cars, let’s at least promote cars that don’t use oil. Electric vehicles and a low carbon electric grid.If we care about the environment and our future, we have to say yes to something realistic. We cannot just scream and yell, be unreasonable and say NO to everything. We have to promote a realistic vision for changes that can be embraced by many.
“forestsareyourfriends, at some point we as environmentalists needs to propose realistic solutions as opposed to simplistic idealism. “Where did I say something that was simplistic idealism? How are technologies that don’t exist yet more realistic than readopting and learning ways of living that have been successful for hundreds to thousands of years longer? Car based culture has not been around for that many years. How are these solutions realistic when the real world (not the economic system) is being destroyed beneath our feet? Tell me what about a 500mpg or cars in general promote local communities? I asked what would the world look like if we worked towards a society with no cars, being that really one with cars can never be sustainable. I would say at some point environmentalists need to believe the natural world is primary and trumps the economic system. At some point we need to put a foot down. At some point we need compromise to not be the first tactic. Its been an utter failure because we aren’t serious enough. “a 500mpg car does not promote local communities.” “Light rail or public buses do not promote local communities either”. Where did I argue with this. You’re arguing with a person that is not me because I did not say that.”But on the same side, a 500 mpg car or light rail or bus system do not prevent local communities. They are not connected issues. It is a non-issue.” A community will be designed around the means of transportation (may it be foot, horse, bike, car, plane whatever) So it is an issue. Why would you need a 500 mpg car in a walkable community? What if the energy towards making cars “SustainableTM” we spent it towards revamping communities to be walkable? Where are the cars made? How are the cars then transported to the community? Does every community make their own cars? Where are all the materials received to do this? The culture we live in is unsustainable, and you cannot take technology out of context.”Poverty does not promote local communities. If we destroy all jobs, that will promote poverty and misery. It will also lead to high crime and fear. “Where did I say we need to destroy all jobs? Its unfair to debate from things I have not even said, that’s a disingenuous debate tactic. How about if you want to challenge me challenge what I say, not what you think I said, or what you have heard other people say. I know poverty doesn’t promote local communities. I work with high poverty (at a HUD housing community center) I see it and am in it everyday. Cars don’t mean jobs, cars don’t mean all jobs are destroyed. That’s a pretty big presumption. I had to get rid of mine because it was so expensive. I had to choose between food or gas. By continuing to make cars primary many others must make the same choices. The residents I live and work with make less than 6000 dollars. Where are they going to get the money to get a new hip sexy car? What they need is a community that isn’t designed for cars. “We need to stay on topic.”How was I off topic, I believe asking what we want is a very important question. Atleast I am addressing things that were actually said. “Let’s face it, with out current infrastructure, which is too late to demolish and replace 100%, this requires individual transportation (ie cars). So if we have to have cars, let’s at least promote cars that don’t use oil. Electric vehicles and a low carbon electric grid. “We don’t have to have cars. Why defeat yourself without even trying? We don’t need to live with cars. That’s the whole point. We won’t have cars in our life time if we like it or not. Sure I rather have cars that are less destructive than more destructive, but that’s not what I am working towards. So if thats what you believe go ahead and work towards that, i won’t stop you. but don’t stop me towards what I am working towards.”If we care about the environment and our future, we have to say yes to something realistic.”You are completely right. But a culture of addicts will define reality a lot differently. What we need to do is base our decisions on what the planet needs. We wont have nothing if we don’t have a healthy planet.” We cannot just scream and yell, be unreasonable and say NO to everything.”Where did I say no? How about you challenge me not someone you are making up. I said is this what we want. In an early post I said I am supportive of making cars more efficient, but it is not a solution and it is not an answer.”We have to promote a realistic vision for changes that can be embraced by many.”Yea and those dependent on cars are not the many. What about the indigenous the world over? What about polar bears? Owls? Newts? Song birds? Fish? Trees? Grass? Those who live with out cars vastly outnumber those dependent on them. There is more than one way to live on the world.
Eric’s contention downplays the potential of Plug-in Hybrid vehicle technology. In order for the debate to be broadened, this potential must be elaborated upon. I wrote briefly of these benefits in the earlier, but Eric didn’t integrate them into his argument. Eric has an immature understanding about walking, bicycling, mass transit and community building, and does not (apparently) realize how the limited driving range of battery-only electric propulsion of plug-in hybrids leads toward fulfilling the goal of multimodal travel and transport: A plug-in hybrid vehicle, (which can be as small as a Prius or as large as a Ford Expedition) offers a limited battery-only driving range of 10-20 miles or so. Since the electric range is (or theoretically will remain) less expensive than any fuel, an economic incentive to drive less is created. In time, future development patterns create destinations that are accessable without having to drive. Walking and bicycling become more viable travel options, the ability to structure mass transit becomes more practical, and the local economic development of community building being sought should follow hand in hand. Just improving mileage, whether 13-to-17mpg or 50-to-500mpg, goes furthest toward achieving the higher goal via plug-in hybrid technology. Added to this complex goal, the plug-in hybrid vehicle is a perfect technological match with rooftop photovoltiac panel solar power which will prove invaluable in an emergency, grid failure or utility price gouging. And the household with this back-up power supply has an excellent means to strictly monitor other household electricity consumption and further energy conservation. It bugs me to read such nonsense as, “becoming a vegetarian reduces more greenhouse gas than driving a hybrid”, or “hybrid battery production cancels environmental gains”, and your bit about SUVs, and so forth from the progressive community. The automobile industry should and probably will develop plug-in hybrid conversion kits and issue recalls, but they will delay this eventuality based on ignorant arguments presented by psuedo-environmentalists like Eric dePlace.
I agree that banning inefficient cars and SUVs is a good idea, but I wouldn’t stop at 15 or 18 mpg. Why not 25? That way, we might actually get rid of the biggest ones completely and we’d all be better off!Another point, though, is even tougher for some folks to swallow. If we don’t stop creating more and more people and, in terms of just the USA, letting more and more people in, than we will find ourselves fighting a losing battle.
IF the greatest oomph is to be found in boosting the lower end, why has no one focused on finding a way to improve the performance, or convert, some of the older engines. A lot of my friends pop engines in and out of race vehicles for street legal vs racing. And I know that some would need a less eco engine for specific purposes. Since its so easy to swap an engine (yes, I have done it myself, with a friend, in my CRV and a Corolla), why don’t we have a version that could go in say the classic cars or a bigger truck so that you could have the power or performance on demand, but for other driving use the more efficient one?And it sounds as though it would not even need to be a hybrid or other transition. It could just be a modified one that that boosted mpg by a bit (say taking that 12 mpg to 20)Just wondering…
This is acting with false assumptions. As shown in Gustafson’s Law if you scale the problem appropriately to all the autos in America, then you once again acheive the 2x efficiency by scaling from 50mpg to 100mpg
I recall reading somewhere that the US Air Force uses more fuel than any other group. Maybe focusing on military fuel efficiency would be fruitful.
Just ending the active wars would cut military fuel comsumption by 1/3.
Many points were made and I’ve only time to comment on a few:Electric vehicles: It’s only a matter of energy distribution how you power a vehicle. With the existing power grid you go from a 15mpg vehicle to a ~25mpg vehicle due to more efficient energy conversion, no further. You can use renewable energy sources, but you don’t have to go electric. You can use water, air, biomass to convert energy to gasoline that you can use in existing vehicles without any net carbon emissions.Minimum-milage standard: There has to be an incentive to use less gas for it to have any effect. A legal MPG limit has the opposite effect. It maximizes the fuel consumption within the legal limit since nothing drives manufacturers to improve MPG. It is only the threat of tighter standards that would drive them to do so.Miles/gallon or gallons per mile: Sure the latter is better illustrating the effect on society. But it is not illustration that is needed, it is action! Why would we like to use less carbon fuel? Because we hurt someone, ie. everybody, and we should compensate everybody for this damage. This would set a price for carbon emissions that would drive the energy consumption to sustainable levels (they exist!). And make manufacturers follow demand for better technology.
Another thing to consider is that we MUST STOP CONFLATING oil with energy. MANDATE FLEXFUEL!!!!!!!Add a $ 100 mod to EVERY car sold in the US, new or USED. The premium pumps & the gas stations will quickly get alternate fuels instead of gas. We’ll still be burning carbon, but the foreign oil problem gets an immediate reduction. If Brazil doesn’t burn gas why should we?
I dont disagree with this blog post..
Boo I ain't nun
Outlawing cars under 18-15mpg will only further enpoverish the lower class and contribute to the poverty trap.
Just get V4 you will be fine.