This never fails to fascinate me:
The chart shows how much fuel is consumed over 15,000 miles by cars of different fuel efficiencies.
The curve matters a lot. It means that from the perspective of fuel conservation, it's not terribly important to trade in your Honda Civic to buy a Prius. But it's hugely important to trade in your Dodge Durango for a Toyota Tacoma.
I'll use some rough numbers to illustrate. You trade in your Civic, which averages about 32 miles per gallon, and buy a Prius, which gets a whopping 47 mpg. You've bumped up by 15 mpg -- a big deal, right?
Sort of. Over the next 15,000 miles of driving, you'll have reduced your fuel consumption by 150 gallons. That's fine. But consider what happens when you upgrade your SUV. That's where the real action is.
You swap out your Dodge Durango (16 mpg on average) for a Toyota Tacoma (23 mpg). It's an upgrade of just 7 miles per gallon. It seems tiny. But consider that over the next 15,000 miles, you will have saved 285 gallons of fuel -- nearly double what your fuel-sipping neighbor saved.
It's a mind-bender, I know. But that's math for you. And that's what the chart illustrates. If we want to maximize fuel conservation, we need to concentrate on places where we can move quickly down the steep part of the curve. Once we've gotten down to the corner -- around 25 or 30 miles per gallon -- we won't get nearly the payoff from efficiency improvements.
Incidentally, this matters a lot for climate policy too. Each gallon of fuel burned translates directly into about 20 pounds of carbon dioxide in the atmosophere. So the curve applies equally to fuel economy and global warming.
Okay, enough pedantry. Here are the take-away lessons:
- To reduce fuel use, our public policies should focus on small upgrades to the least efficient vehicles. It's less important to tinker at the upper end. The biggest gains are at the low end -- and small improvements make an enormous difference.
- The U.S. should take a cue from Canada. We should talk about "gallons per mile," not "miles per gallon." (North of the border, of course, it's litres per kilometre.) "Gallons per mile" makes it much, much easier to see where the problem lies -- at the low end.
My boss, Clark Williams-Derry, has looked at this phenomenon before. You can find his insights here, here, and most importantly, here.
Cash for Clunkers brought us ... more clunkers!
Comments
View as Flat
odograph Posted 4:24 am
20 Dec 2007
I think it's a false perception that the 1/2 of the US market who buys SUVs needs them.
Getting folks out of the worst SUVs is the most important goal, and the further you move them in that leap, the better.
Permalink
sindark Posted 4:33 am
20 Dec 2007
a sibilant intake of breath
Permalink
justlou Posted 4:52 am
20 Dec 2007
Permalink
Eric de Place Posted 4:56 am
20 Dec 2007
I just think it's interesting that the low-end improvements make a bigger difference than the upper-end fixes.
Permalink
greenfyre Posted 5:03 am
20 Dec 2007
If it is perspective that you are after put that on the graph when comparing fuel savings.
And please refrain from using the word "need" in reference to what is for 90% of the urban population an outrageous luxury ... it is so insulting patronizing to the huge proportion of the population that do not indulge themselves in that way, never mind the majority of the globes population who are being made to pay for our indulgences.
Permalink
PolluteLessDotCom Posted 5:44 am
20 Dec 2007
Can't say I am surprised.
That is EXACTLY why we need to focus on the habit changes that are relevant rather than on those that are currently so popular but make basically no difference. And that is why any "green" advice needs to be judged for its impact. Not every bit matters.
Karsten
--
http://www.polluteless.com
Practical Advice to Pollute Less
Permalink
mnmahult Posted 5:56 am
20 Dec 2007
Getting the already concerned driver to be more concerned is not nearly as important as getting the driver who doesn't really care to truly care. And buying a truck getting a measly 23 mpg is not caring. That's like the 'green' living in a 3500 sq foot house talking about their 400 sq ft yoga room with the fireplace made from locally harvested river rock. Whatever. Don't build the yoga room, and don't buy the monster truck. Unless you work on a ranch, or spend a lot of time hauling construction material, there is no excuse for owning a behemoth. Finally, while the percentage change in moving from 16 to 23 might be greater than the change seen when moving from 32 to 47, how about the percentage change, and the fuel saved, by moving from 16 to 47? That change might do something beside just slow climate change down a bit.
Permalink
Sam Wells Posted 6:19 am
20 Dec 2007
It is also why the CAFE standards would have a marginal effect at best, by 2020 or something.
If you take a SUV and crush it, killing the engine, and hopefully recycling it carefully, you might have done some good.
Note that if you trade off a stinky old SUV and buy another clean machine, you have ADDED to global warming. Didn't know that, did you?
Oh man, who cut the cheese in here?
Onward through the fog
Permalink
GreenEngineer Posted 6:25 am
20 Dec 2007
Disclaimer: I don't know details of how CAFE is calculated, but my understanding is that it is the average fuel economy of all the models a particular manufacturer produces, weighted for the number of each type of car that gets made. And I'm totally ignoring the flex-fuel/biofuels loophole.
That said, if I'm correct, then CAFE is a really bad way to control gasoline consumption (or air pollution, or anything else related).
If you have one car that gets 20 MPG and one that get 60 MPG, your CAFE is 40 MPG.
To travel 10,000 miles, the 20MPG car uses 500 gallons, and the 60 MPG car uses 167 gallons (not bad for a year's gas consumption). Total is 667 gallons.
Whereas a car that actually gets 40 MPG uses 250 gallons to go 10,000 miles. To make it equivalent, two such cars use 500 gallons to drive that distance.
The upshot is that a manufacturer who builds high-efficiency hybrids to offset their gas guzzlers complies with CAFE, but does much more harm to the planet than a manufacturer who builds moderately efficient cars across the board.
Yes, I realize that 40 MPG is better than "moderately efficient", but I picked the numbers because they're easy to work with. The math holds regardless of the figures you choose. And, in point of fact, China's minimum fuel economy standard will rise to 43 MPG in 2008, and they look at individual vehicle figures, not fleet figures.
Permalink
Donald Hawkins Posted 6:44 am
20 Dec 2007
Well I've got a hammer
And I've got a bell
And I've got a song to sing
All over this land
Everybody then yelled hurray and they to began to sing,
Well I've got a hammer
And I've got a bell
And I've got a song to sing
All over this land
It's the hammer of justice
It's the bell of freedom
It's the song about love between my brothers and my sisters
All over this land
It was wonderful.
Don
Permalink
odograph Posted 6:45 am
20 Dec 2007
"Note that if you trade off a stinky old SUV and buy another clean machine, you have ADDED to global warming. Didn't know that, did you?"
Like everything, it's complicated. Yes, you'd need to scrap a car to be sure it logged no more miles. But the good news is that VMT (vehicle miles traveled) does decline with vehicle age, and 2nd and 3rd owners do tend to drive less than 1st ones.
But we could hasten that, if we had the guts, say by increasing vehicle registration fees for gas hogs.
Permalink
mnmahult Posted 7:04 am
20 Dec 2007
I think we're arguing different points. When someone trades in for a new car, they may already be making a decision that's unwise for the planet. But I had read Eric's posting as saying that when you trade up to a better SUV you're doing good. My argument is that if people buy new cars, as we know they will, the damage done will be less when they buy a Prius or other "high" mileage vehicle, than when they buy a vehicle getting 23 mpg. I think it's hard to argue that buying a new car is good for the planet, when the one you own now still runs. It's better to not drive, or drive as little as possible. But when push comes to shove, and Mr. Smith decides his 16 mpg truck is no longer good enough, I hope he opts for the 47 mpg Prius, and not the 23 mpg anything.
Permalink
Jon Rynn Posted 7:23 am
20 Dec 2007
If you had a car that got 50 miles per gallon (mpg), you would use .02 gallons per mile. If you traded up to a car that got 100 mpg (!), you would use .01 gallons per mile, or a savings of .01 gallon per mile.
If you had a gas guzzler that got 16 mpg, you would use .0625 gallons per mile. If you traded up to a gas guzzler that got only 20 mpg, you would use .05 gallons per mile, for a savings of .0125 gallons per mile.
So if you traded up from 16 mpg to 20 mpg, you'd save more gasoline than if you traded up from 50 mpg to 100 mpg!
Permalink
odograph Posted 7:29 am
20 Dec 2007
What we've got to hope is that somewhere down the line an old pickup of SUV will be bumped off the road. Heck, we see the "for sale" signs come out when gas prices rise. Freely available smaller used cars, as we add them to the fleet, help that.
People still make the bad argument that "poor people need to drive old gas hogs," but this isn't the 80's. We've been adding higher MPG cars to the fleet for a long time.
And of course the truly poor don't have cars in the first place.
Permalink
Eric de Place Posted 7:58 am
20 Dec 2007
You save more gasoline trading from 15 to 18 than you do trading from 50 to 100.
Permalink
Jon Rynn Posted 9:34 am
20 Dec 2007
Odo -- At most the energy to make a car is 20% of the lifecycle -- there was a study that flipped the numbers, were you the one who pointed that out, or did somebody else? The amount of electricity used to make things is fairly low.
Permalink
Ron Steenblik Posted 9:42 am
20 Dec 2007
If Canada and (slowly) Britain could do it, why not the USA?
In Europe, fuel ratings are already expressed in terms of litres per 100 km.
Permalink
spaceshaper Posted 11:21 am
20 Dec 2007
So buy a tank first for your daily commute so you can save even further by trading to an armored personnel carrier? Truly these numbers are entertaining - sort of - but essentially meaningless, unless we were to be in a situation where there were not enough better mileage cars to go around. Outside of that scenario, it's not about maximizing how much you save but about minimizing how much you use.
Interesting though. Like the paradox that folks who keep their driving to a minimum are the last people who would be allowed to buy a Prius if they were rationed, but are often the first ones to do so in our free market of endless abundance.
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
Jon Rynn Posted 1:08 pm
20 Dec 2007
Permalink
Delay And Deny Posted 1:16 pm
20 Dec 2007
I already have described in the Comments of Grist data that show that much of the mileage increase for a hybrid comes from lack of idling -- which in a standard gas engine can account for about 20 percent of energy loss.
Couple that with the above chart, and you could say that if people who drove really inefficient cars turned off the engine when at a stop sign or while waiting in traffic, or waiting for someone for more than 30 seconds (that's what I've read is the point at which the savings exceeds the loss from ignition) we would essentially automaticallyboost gas mileage for city driving.
A better solution would be some kind of computer control that shuts down the engine (a sort of reverse cruise control) when idling -- or even, when going downhill for a long period on highways after exceeding a certain speed.
That essentially would give a standard car all the benefits of a "hybrid" without having the added burden of carrying around two engines and two storage systems.
My Log
Permalink
GreenMom Posted 2:13 pm
20 Dec 2007
If you really want to make a difference, push for more financial support for truck stop electrification. Think about all the 18-wheelers out there who idle all night to keep their cargo refrigerated, their butts warm, and their DVD players running.
A bunch of states, my own included, have pilot projects where they're giving some grant money to truck stop owners to provide truckers the means to plug in instead.
Talk about massive benefits. Everybody wins.
Permalink
katakanadian Posted 4:05 pm
20 Dec 2007
I would agree that 30 seconds is an appropriate limit.
Some people claim they need a really long warmup but I would say that more likely they need some repairs and maintenance done (unless they are dealing with -40 degrees). My 27 year old Corolla needs about a minute in the first startup of the day or it stalls, later in the day it only needs 5-10 seconds.
Permalink
Ron Steenblik Posted 5:06 pm
20 Dec 2007
[I]f one were willing to think about radical policy alternatives ... instead of CAFE standards for the whole national car fleet, you ban cars under a certain mile per gallon: start at, say, 20 miles per gallon and then keep going up.
There is already precedent for such a policy: minimum energy-performance standards (MEPS) for electrical appliances. Within specified categories of air conditioners, freezers, refrigerators, etc., you just cannot buy ones that do not meet the MEPS. Of course, at the same time, there is nothing preventing people buying, say, a walk-in freezer and installing it in their home.
Do I think establishing a MEPS regime for vehicles would be politically feasible in the United States? Nope. Even in Europe, an individual can buy a Hummer. But you would have to mortgage your home to afford the fuel (now over $8 per gallon in most countries), and try finding a legal parking space for it!
Permalink
John Fish Kurmann Posted 5:58 pm
20 Dec 2007
A better solution would be some kind of computer control that shuts down the engine (a sort of reverse cruise control) when idling -- or even, when going downhill for a long period on highways after exceeding a certain speed.
That essentially would give a standard car all the benefits of a "hybrid" without having the added burden of carrying around two engines and two storage systems.
This claim isn't any more true posted here than it was when you posted it to the "Prius smackdown, round two" blog. Yes, the stop-start function contributes to the fuel economy savings of hybrids, but it isn't even close to the primary contributor. Here's how I explained it before:
The main efficiency gain of a hybrid comes from the fact that the electric motor provides a significant portion of the energy needed to move the vehicle by capturing, storing, and then using energy generated during braking and while cruising that goes to waste in conventional cars. Some hybrids--those classified as full hybrids--even move using the electric motor and battery pack alone under certain circumstances, such as stop-and-go traffic. Full hybrids include all Toyota hybrids, Honda's 2nd-generation Civic Hybrid, Ford's Escape and Mariner Hybrids, and General Motors' upcoming 2-mode hybrids (hybrid versions of the Chevy Tahoe/GMC Yukon/Cadillac Escalade and the Chevy Silverado/GMC Sierra pickup).
Mild hybrids, in contrast, derive a significant amount of their motive power from the electric motor and battery pack but cannot be driven on the electric motor alone. Mild hybrids include the 1st generation Civic Hybrid as well as the discontinued Honda Insight and Accord Hybrids.
Then there are vehicles which do receive a slight acceleration boost from their electric motors and battery packs, but their systems are so weak that the Union of Concerned Scientists classifies them as "hollow hybrids." Vehicles that fit this description include the Saturn Vue and Aura Greenline variants and the new Chevy Malibu "Hybrid."
Okay, let's look at a real-world comparison. Since there's no conventional version of the Prius, I'll use the conventional and hybrid versions of the Honda Civic as examples:
The conventional Civic (whether equipped with a manual or automatic transmission) is rated at 29 MPG combined city/highway while the Civic Hybrid is rated at 42 combined. That's just shy of a 45% increase in fuel economy. According to the EPA, stop/start systems (which they call "Integrated Starter/Generator" systems) improve fuel economy 8%.
In other words, stop-start systems, though contributing significantly to improved fuel economy, are not the primary reason that hybrids are more fuel-efficient than comparable conventional vehicles.
Even so, it would provide significant fuel economy benefits if every automaker made stop/start systems standard on all their models, and they could do it without adding much to the price of a car--Chrysler claims "several hundred dollars."
The world is sacred, and I am part of it.
Permalink
Nucbuddy Posted 8:41 pm
20 Dec 2007
The formula is right here:
nhtsa.dot.gov/cars/rules/cafe/overview.htm
The averaging method used is referred to as a "harmonic mean".
Averaging according to a harmonic mean method (which basically means averaging the reciprocals) accomodates for the potential averaging-problem you pointed-out in your comment.
GreenEngineer wrote: If you have one car that gets 20 MPG and one that get 60 MPG, your CAFE is 40 MPG.
No, the CAFE harmonic-mean method would say that you have a CAFE of 30 mpg. The CAFE harmonic-mean method would not add 20 mpg to 60 mpg and then divide by two. It would divide 1 by 20, add that to (1 divided by 60), and divide 2 by that sum. The result would be an average 30 mpg, which would equal a summed gasoline usage for both vehicles of 667 gallons over 10,000 miles -- exactly as you calculated it should be.
In comparison, two 40 mpg vehicle would indeed be calculated at an average of 40 mpg and together would use only 500 gallons of gasoline over 10,000 miles.
Therefore, the CAFE methodology -- because it calculates according to a harmonic-mean -- does indeed recognize the superior fuel-economy of two 40 mpg vehicles vs. one 20 mpg vehicle summed with one 60 mpg vehicle.
Permalink
odograph Posted 10:33 pm
20 Dec 2007
Wikipedia covers it as:
CNW's publication "From Dust to Dust" [1] claims that a Hummer is more efficient than a Prius, despite the fact that a Prius is one-third the weight of a hummer and gets between four and six times better mileage. CNW claims that their efficiencies are based on Priuses lasting only 109,000 miles whilst Hummers run for more then 300,000. Neither of these figures are properly documented and this study has been roundly debunked.
Permalink
Sean Casten Posted 10:59 pm
20 Dec 2007
The fun part though was data that they had put together assessing various policy options, which essentially showed (rather compellingly, I thought) that rather than mandating that all new cars install next-generation catalytic converters at a cost of $100/car (or some similar #), there would be a much bigger bang for the buck if the state simply paid every owner of a 1971 Dodge Dart or similar vintage, uncontrolled, vehicle $10,000 to get them into a new, cleaner ride. This would not only have cost the state less $, but would also lead to a greater increase in pollution reduction. The math worked for the simple reason that most of the pollution comes from a fairly small subset of vehicles. Get those vehicles off the road first and all other good things follow.
Needless to say, the argument did not resonate with CA, but I've always found it rather intriguing. Maybe a policy idea for those Durango drivers today?
Permalink
odograph Posted 12:32 am
21 Dec 2007
Giving monies the government doesn't have to consumers who are spending monies they don't have is certainly the current zeitgeist
but I'd prefer a little less debt all around, and straight up taxes on things we don't like, like gas hogs.
Permalink
spaceshaper Posted 12:36 am
21 Dec 2007
If it was a tough sell to pay to junk a '71 Dart with a 10K bribe (several times what the car would have been worth), what'd you have to pay to junk a 2006 Durango to make it worth the owner's while?
While we're on the subject of diverse analytical perspectives, the Hummer/Prius lifetime energy study was debunked partly because it took the Prius' effective life to be 100K miles and the Hummer's to be 300K. The sensible point was made that the Prius was also mechanically capable of 300K miles.
But consider the not entirely unlikely scenario in which a Prius is driven only 5K miles a year by an environmentally responsible owner and is surpassed in efficiency by far more technically advanced vehicles within ten years, to the extent that like the Dart (and like the Hummer too of course) it needs to be consigned to the scrapheap - with only 50K on the dial. The widely-quoted average lifetime energy costs ratio of 20% manufacture/80% use might easily be reversed in such a context, largely demolishing any environmental-impact advantage that vehicle might seem to offer. And guess what: this effect will only increase for the more fuel-efficient replacement technology unless there's also some truly miraculous improvement in the energy costs of manufacture. Something to bear in mind.
I'm not making this point to denigrate the Prius or any other relatively fuel-efficient vehicle. I'm just pointing out there are a number of questionable steady-state assumptions in these analyses, and that "better fuel efficiency" is something of a chimerical goal.
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
DarthPetrol Posted 12:40 am
21 Dec 2007
Administerd by the Texas Commission on Environmental Quality, the state will pay you up to $3,500 to trade in your 10-year old car. Unfortunately there is an income cap on this benefit. It seems to me that if your primary interest is in cleaning up the environment you wouldn't care who took you up on the offer.
That reminds me, whatever happened to Englehard's PremAir system? PremAir removes ground level ozone and CO. The catalyst is used in a popular air purifying system. Initially cost was an issue, but they aren't using platinum in the current system.
Permalink
amazingdrx Posted 1:35 am
21 Dec 2007
Anyway... I like Lovins' math much better. This, replace one SUV/truck for a more efficient one argument seems deceptive somehow.
Amory points out that only .03 % of the energy in the gas is actually used to move the weight of the passengers.
But, cry the SUV owners, a heavier vehicle is safer. Or, I need a large vehicle to haul the kids around on my turn in the car pool.
Big does not necessarily mean heavy though and light does not mean unsafe. Racecars are the safest vehicles and also the lightest.
Subsidies should target making all vehicles lighter AND safer, especially gas guzzlers. And shifting from the SUV to an economy car. Instead tax breaks still favor big heavy SUVs and trucks.
I saw a monster SUV with a local tax service logo on the side yesterday. Uh huh, you guessed it, they aren't hauling tax forms around in that gas guzzler. But they get the 100k tax break anyway.
http://amazngdrx.blogharbor.com/blog
Permalink
Sean Casten Posted 2:00 am
21 Dec 2007
As I recall (although it may have been another article), the wonder of the whole SUV/safety angle is that it is a marketing success independent of reality. One of the big 3 (Ford maybe?) did a study where they had people sit in cars that were all slightly different and then asked them a series of questions designed to identify what factors made people perceive that they were in a safer car. One of the more remarkable findings was that the number of cupholders correlates strongly with perceived safety.
There is something Freudian there, in the return-to-the-womb-with-my-never-ending-supply-of-food-and -beverage-and-soft-velvety-interiors-when-everything-was-safe-and-warm implications. But the larger point is that if you put someone high off the road in a soft-suspension with lots of creature comforts and cupholders they will end up buying on a perception of safety that largely ignores the fact that being high off the road, losing the tight-suspension that gives you responsiveness to avoid a collision and adding in all sorts of creature comforts (i.e., distractions) are actually making the car less safe.
Permalink
trock Posted 2:53 am
21 Dec 2007
The one huge SUV won in that it did get better gas (diesel) mileage than the sum of all 3 fuel-efficient vehicles. The fuel-efficient vehicles did think they would have won if for not bad planning of the media events. The media events took longer than they thought they would so the group of vehicles had to speed to get to the next one, giving the one speeding vehicle an advantage over 3 speeding vehicles. But they made their point just as well. (I suppose)
Permalink
GreyFlcn Posted 2:54 am
21 Dec 2007
Because it puts an exponential burden on the low end of the MPG spectrum.
Where as CAFE only puts a linear burden.
Permalink
amazingdrx Posted 3:12 am
21 Dec 2007
That kind of redesign deserves the most subsidies, because it saves the most gas and GHG. When will we have Nerf SUVs, with a thin skin of carbon fiber aluminum sandwhich?
That would be off the chart!
http://amazngdrx.blogharbor.com/blog
Permalink
John Fish Kurmann Posted 2:30 am
22 Dec 2007
Your point that newer vehicle technologies may make today's iconically-"green" Prius look old, dirty, and inefficient in the foreseeable future doesn't really make sense to me. It seems clear to me that, under the prevailing market economy, we'll never see a day in which everyone can afford the latest, most-efficient, and least-polluting vehicle, and we're not at the point where society at large has determined that it's in our interests to ensure everyone has the best available vehicle technology, so we can expect there to continue to be a large market for used vehicles in the future (barring dramatic change in our economic system, which is by no means outside the realm of possibility but not important to my point). Isn't it better for the affordable used vehicles to be Priuses and Civic Hybrids and Honda Insights rather than Durangos and '71 Darts?
I'm a perfect example: I'd like to have bought a Prius, but the most I could afford was a model year 2000 Honda Insight with just shy of 104,000 miles on it, which I paid $7,500 for, roughly 1/2 what a Prius would've cost. On the upside, I've averaged 60.3 MPG year-round since I got it, which I couldn't have achieved in a Prius.
In other words, I think it's highly unlikely that any new vehicle technologies will be introduced over the next 10 or even 20 years which will be so much more efficient and clean--and readily available--that they'll consign today's Priuses to the scrap-heap even though the Priuses will have a lot of miles left in them.
The world is sacred, and I am part of it.
Permalink
John Fish Kurmann Posted 2:56 am
22 Dec 2007
I do want to note that the article was published almost 4 years ago now, and to some extent it's been outdated by technological development. What I mean by that is many--perhaps most--SUVs now either have electronic stability control (ESC) systems standard or available as options, and ESC significantly reduces some of the increased risk of SUVs by overriding driver decisions that can cause the driver to lose control of the vehicle, leading to crashes and rollovers. SUVs are still typically less-nimble and take longer to stop than cars, though, which are very important factors in what is called "active safety"--the ability to avoid getting into a crash or collision. The large mass and height of SUVs typically do give them advantages in "passive safety," which refers to protection in a crash or collision.
It seems clear to me that the safest vehicles are those which strike a good combination of active and passive safety, including secure handling, short stopping distances, strong structural design, and a full complement of airbags. Fortunately, the 3rd generation Toyota Prius (the hatchback version), when equipped with side airbags (optional on model years 2004-6, standard thereafter) does strike a good balance of all these features, though its crash test ratings aren't as high as I'd like. The Toyota Camry hybrid, for one, has better crash test ratings, but I'd trade that small loss in passive safety for the extra 12 MPG in the Prius (combined city/highway) if I was buying a new car.
I think it's important to keep in mind that people didn't switch to SUVs because they wanted to burn more fuel and set the planet on fire but because they honestly perceived them to be safer than cars--and sexier than minivans. If we want to get people out of SUVs and into more efficient vehicles, we need to show them really safe options that meet their need for status, too. We shouldn't expect berating or making fun of them to do any good.
The world is sacred, and I am part of it.
Permalink
spaceshaper Posted 4:16 am
22 Dec 2007
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
John Fish Kurmann Posted 5:18 am
22 Dec 2007
One thing we need to keep in mind when we talk about the relative energy-saving benefits of vehicle-switching is to compare vehicles with comparable utility. Your example comparing a Dodge Durango to a Toyota Tacoma doesn't really hold up in this regard because the Durango is a large SUV while the Tacoma is a midsize pickup. Someone who wants the interior hauling capacity offered by a Durango isn't going to be satisfied with an open-bed pickup, not even an extended-cab version with a backseat. It makes much more sense to me to compare vehicles with similar passenger and cargo capacities that have significantly different fuel economy ratings. There are a variety of ways automakers can dramatically improve fuel economy in vehicles with comparable utility without going so far as adding hybrid systems. Automakers could opt to use less-powerful engines (average horsepower has increased to an absurd degree over the last 20 years, to the point where some "family sedans" accelerate as quickly as muscle cars used to) as well as to improve the efficiency of their engines (cylinder-deactivation systems are one example). Automakers could also make vehicles smaller (or at least keep them the same size) and lighter when they introduce redesigned models, rather than continuing the trend of bigger-and-heavier at each redesign. And these are choices that buyers often can make right now, opting for 4 or 6-cylinder crossovers rather than 6 or 8-cylinder SUVs, if they are willing to place more emphasis on reducing fuel use and emissions than acceleration or that SUV "presence."
We also need to figure out how to persuade people who are going to buy a new vehicle to make their decision on the basis of their daily rather than their occasional needs. Too many people choose a vehicle based on their desire to be able to haul home a load of lumber or a passel of people in their vehicle--which they rarely actually do--rather than their normal commuting needs when they could borrow or rent trucks/vans when they need that much capacity.
To put it another way, rather than comparing a Durango to a Tacoma, I'd compare a Durango to a Toyota Highlander. No, it's not a perfect comparison: The Highlander isn't quite as large, but it does offer 3 rows of seats like the Durango. The Highlander doesn't have the towing capacity of a Durango, either, but how many people need to be able to tow a huge trailer 365 days a year?
The Highlander is what's called a crossover SUV, meaning that, though it has that basic SUV shape and sits fairly high off the ground, it's derived from a car (the Toyota Avalon) rather than a truck platform; the Durango is derived from the Dodge Ram truck. The Highlander is also front-wheel drive while the Durango is rear-wheel drive. These differences as well as the Highlander's somewhat smaller size result in the 2WD V-6 Highlander achieving a fuel economy rating of 20 MPG combined while the 2WD V-6 Durango is rated at 16 MPG combined--that is, you get 25% better fuel economy in the Highlander.
And, for those who could afford the premium for the hybrid version of the Highlander--which is only available as a four-wheel drive (4WD) vehicle--the bump would be from 15 MPG combined for a 4WD Durango to 26 MPG combined for the Highlander Hybrid--a 73% increase in fuel economy.
The world is sacred, and I am part of it.
Permalink
John Fish Kurmann Posted 5:33 am
22 Dec 2007
I'm not sure we agree as much as you seem to me to think we do. The way I see it, as long as people are going to buy new vehicles, I think we should encourage them to buy the most-efficient, least-polluting vehicles they can afford that meet their daily needs--hybrids, where possible. Though vehicle technology may well improve dramatically over the next 10 years, I still think it will be better to have a large rather than a small percentage of hybrids in the used vehicle market.
Regarding lifetime vehicle energy consumption, the Union of Concerned Scientists had the following to say:
A variety of reputable investigators have concluded that 85-90 percent of energy use and global warming emissions attributable to an average vehicle over its entire lifecycle come from operation. Only 10-15 percent is production and disposal. This is true for both hybrids and conventional vehicles.
In order to achieve a net reduction in per-mile global warming emissions, (i.e. to offset the additional emissions from manufacturing and disposing of another vehicle) the new vehicle will have to get 10-20 percent better fuel economy than the old vehicle, assuming the vehicle will be driven in a typical way (i.e. that it will be used for its full useful life - usually around 170,000 miles).
The UCS give more detail on that page as to how and when it makes sense to buy a new car rather than continuing to drive the vehicle you have.
Given that I'm getting higher MPG in my used Insight than I would've in a new Prius, this doesn't apply to me--but I'm a single guy, so a tiny, 2-seat hybrid is adequate for my needs.
The world is sacred, and I am part of it.
Permalink
spaceshaper Posted 9:21 am
22 Dec 2007
The effect would also be expected to increase the more elaborate the technology needed to achieve that efficiency as more disparate components from more places are brought together for assembly. And I find it especially hard to understand the claim that the production/use ratio is the same for a hybrid as for a non-hybrid. This would mean that if the hybrid burns say 30% less gas during its lifetime than the comparable vehicle it would also need to consume 30% less energy in its production and disposal to maintain the ratio: this for an automobile with two separate drive trains and two separate energy media. And if it were somehow possible to so hugely reduce production energy costs for the hybrid, why not do it also for the regular auto?
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
spaceshaper Posted 9:51 am
22 Dec 2007
In case it's not clear from what I wrote earlier, I feel that this a big assumption that may not be true for many buyers. A green-thinking owner driving 5,000 miles a year would take 34 years to take the Prius through its "full useful life", and few cars last that long for reasons outside of drive-train durability. Therefore, IF you're that kind of driver, you'd need to be looking at far better than 10-20% mpg improvement to justify the environmental cost of the new vehicle.
And of course, if you're an average 15K a year driver, far better to find a way to substantially CUT your annual mileage by two thirds than to buy any kind of new vehicle.
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
John Fish Kurmann Posted 4:10 pm
22 Dec 2007
While I see your point about the hypothetical Prius driver who only puts 5,000 miles a year on her/his car, that driver is only hypothetical, and I bet there aren't too many real drivers who fit that description. I imagine most Priuses get driven not too many fewer miles than conventional cars simply because of the realities of U.S. development patterns. Take me, for example:
While I certainly consider myself "green-thinking," and though I walk and use the bus here in metro-Kansas City when feasible, I've put about 12,000 miles on my Honda Insight this year. Why? Because I live in what's called the northland, the part of Kansas City, Missouri that's north of the Missouri River, and bus service out here is meager at best. It's somewhat better in the heart of the city, but I have to be able to get to and from the heart of the city to take advantage of that better service and that's not always feasible--so I drive much more than I would in my ideal living situation (where I wouldn't have cause to drive at all). I could theoretically move to the heart of the city (and likely will at some point), but the higher rent and insurance costs would require taking a regular job, which would leave me less time for my activism--ah, tradeoffs.
On the upside, a Prius does get more than 10-20% better fuel economy than a conventional car--much more. There's no conventional version of the Prius, but the most comparable other model Toyota makes is the Matrix. The most fuel-efficient version of the Matrix achieves an EPA combined city/highway rating of 29 MPG while the Prius rates 46 MPG combined. Doing the math, that means the Prius gets 58% higher fuel economy than the Matrix--not shabby at all.
The world is sacred, and I am part of it.
Permalink
Delay And Deny Posted 5:42 pm
22 Dec 2007
Does Mass Transit Save Energy?
http://www.lafn.org/~dave/trans/energy/does_mt_saveE.html ...
Shows that the increase in energy efficiency of the automobile after 1970 and the decline of mass transit efficiency has resulted in mass transit being little more energy efficient than the auto.
...Conclusion
Neither the automobile nor mass transit will significantly reduce our energy consumption in urban passenger transportation. There is no magic technical fix for the problem, but there is an obvious solution: Simply greatly reduce the amount of travel. This can be encouraged by reducing population so as to provide more available housing so that people can live nearer work. Land use controls should prevent the construction of workplaces unless there is plenty of available housing nearby (within walking or bicycling distance).
My Log
Permalink
John Fish Kurmann Posted 3:40 am
23 Dec 2007
If true--and I don't know enough to evaluate the author's methodology or data--this paper is good incentive to dramatically improve the energy efficiency of mass transit. I also agree with the paper's author that the real solution is to live closer to home--to move us and our stuff around a lot less.
In my case, the bus is going to run whether I ride it or not (to provide transportation to those who cannot afford a car as well as those who cannot or do not drive for other reasons), so it's clearly more energy-wise for me to take the bus when feasible rather than drive my own car. And I improve the energy-efficiency of the system by adding a rider to bus-routes that are generally far from full.
The world is sacred, and I am part of it.
Permalink
Stan1624 Posted 2:54 pm
26 Feb 2008
*Unless we switch to cleaner vehicles, global warming is projected to degrade local ecosystems, seriously disrupt agriculture, and trigger potentially catastropic sea-level rise.
*SUVs emit 40% more global-warming pollution than an average car. In fact, switching from driving an average car to a 13 mpg SUV for one year wastes more energy than leaving a refrigerator door open six years.
*In 2002, SUV drivers paid on average $350/yr more for gas than drivers of average mpg cars.
After learning this facts recently I am now thinking seriously about trading my SUV. I drive a 2007 Durango and I am willing to trade my Dodge parts for some fuel-saving family vehicle.
"if you can't win the race, make the one ahead break the record"
Permalink
chargerplates Posted 3:39 pm
27 Feb 2008
charger platesgold charger platescharger plates
silver charger platesbrown charger plates
green charger platesred charger plates
blue charger platesglass charger plates
Permalink