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The End of the Gas Guzzler
Hugh Pickens writes "Michael Grunwald reports that President Obama will announce today a near-doubling of fuel efficiency standards for cars and light trucks, and the Big Three automakers — GM, Ford and Chrysler — will support it in a final deal that will require vehicle fleets to average 54.5 miles per gallon by 2025, which will reduce fuel consumption by 40% and carbon emissions by 50%. Although environmentalists had pushed for 60 mpg and the White House had floated a compromise of 56.2, 54.5 is pretty close, considering that last year's standards were only 28.3. 'I might point out that the same auto industry that ran attack ads about how 56.2 would destroy their businesses and force everyone to drive electric cars has embraced 54.5 as an achievable target,' writes Grunwald. 'It almost makes you wonder if the automakers may have exaggerated the costs of compliance, the way they always do.'"
Maybe you could, you know, let people buy the vehicles they want to buy and then if gas is expensive most won't buy gas guzzlers?
In this case I'm guessing the auto makers are salivating at the prospect of being 'forced' to load up cars with hybrid crap that will allow them to push up prices and make more profit.
I think it is more don't buy the hand that feeds you.
But buying the hand that feeds you is how politics works.
The Daddy casts sleep on the Baby. The Baby resists!
The real question is will the market bear the new regulations? Americans as a nation have obviously NOT demanded higher MPG ratings from their cars or there would be no need for the regulation. How much more will each vehicle cost to use the higher technology needed to achieve the standards? By setting the standards the government may have artificially increased the market price and will thus affect supply and demand. I'm all for environmental policies, but outside of the academic towers, the real world still intervenes and economics will affect well intentioned government mandates.
This doesn't mean that you'll actually see cars that get 50-60mpg sold in the U.S. The automakers get credits on mpg for adding things that have nothing to do with fuel efficiency (like LED headlights and crap). So you might have a vehicle with a bunch of addons that only gets 35mpg, but the automaker gets credit for a vehicle that gets 50mpg (because they get 15mpg worth of fuel efficiency credits). Not to mention it's an average. If the automaker sells one vehicle that gets 20mpg for $25,000 and one vehicle that gets 100mpg for $60,000, they have a fleet average of 60mpg. It doesn't matter that they sell 10,000 of the 20mpg units and only 500 of the 100mpg units. And trucks get completely different (and drastically lower) standards than cars. It's amazing what you can classify as a "truck" these days.
CAFE is a joke.
More importantly, look at the deadline: 2025. Plenty of time to repeal or reduce the fleet average to a more approachable target, like 24mpg.
greed@All_Evils:~#
New 300 HP luxury sedans are getting 29 MPG now. 54 MPG in 10 years should not be that hard.
The thing to realize is that going from 10 MPG to 20 MPG saves twice as much as going from 20 to 40.
I don't understand what you're saying.
You say that the government is punishing automakers that make large cars and got into significant financial trouble because they lost their market, then you say that the market wants large cars. Then you say that foreign car makers will clean our clocks because they already make lots of small cars...
From my perspective, American automakers got drunk on selling cheap-to-make vehicles expensively. Trucks, classically, cost less than cars. There also were no luxury trucks, as they were designed for utility , not luxury. Granted, a one-ton truck would cost more than a 3/4, and that would cost more than a 1/2, and it's even possible that the heavier-rated trucks would cost a little more than the cheapest cars, but by and large, a half-ton truck was not expensive, until the domestic automakers decided to gussy up their trucks and engage in a clever marketing strategy.
Unfortunately, gas prices caught up with them and the market never recovered, but they still haven't lowered the prices of trucks. Consequently, people now are willing to look at what other countries would consider to be mid-size cars, which we consider small.
Do not look into laser with remaining eye.
Why doesn't Obama require Intel to release the 10 GHz Chip? Apparently the only thing stopping progress is there isn't any legislation mandating it, right? So why stop at 60mpg? Why not 1000 mpg? We should also mandate flying cars and a PONY for EVERYONE!!!
What is up with this imaginary thinking?
Do people really believe everything they think?
Good security is based upon reality and common sense. Common sense is a function of having common knowledge.
Well, since your behavior is punitive to those who can't afford those cars, perhaps you should suffer the consequences?
After all, your behavior is driving the cost of gas up for everyone, not just you. You're overconsuming a limited resource, to the detriment of others who are also dependent on that same resource, but can't afford it as readily as you can.
Is this really that hard to understand?
Of course, the alternative is just to raise the cost of gas. Folks who buy cheaper cars that do better on gas will benefit. You'll feel the pinch, which you should... perhaps not least of which for being a self-absorbed prick.
The real way to tackle this problem is with gas taxes. Raise the cost of gas up to 6 dollars a gallon, and the fleet average will go up, from consumer demand.
It almost makes you wonder if the automakers may have exaggerated the costs of compliance, the way they always do.
I mean really. Was there ever anyone who actually thought that 25mpg was really the best a small sedan could muster?
In 1978, the American roads were filled with a little car, that did 50 EMPG. The Datsun B-210.
http://en.wikipedia.org/wiki/Datsun_B210#B210_series
In 1984, I rode in the back of one with three other passengers, knees-under chin. We went 425 miles to San Francisco, well under a single-tank. Our actual MPG was better than 55, with all that load.
"Speaking the Truth in times of universal deceit is a revolutionary act." -- George Orwell
Uhm, techniques like resin transfer molding using pre-laid or pre-woven fiber structures are scaling well lately - from what I hear out of the business, several German car makers are scaling it for mass production right now. They've been researching the topic like mad in the last couple of years.
Ubi solitudinem faciunt, pacem appellant.
Owing to the rate at which the number of automobiles is increasing, they could reach this goal of lower emissions and better fuel economy, and we'd still be polluting more and using more fuel than we are now.
Granted, it's better that than no improvements at all, but if kept the same end-goal requirements, but shortened that vision to... oh, say 2015 or so... then they might have a chance at actually really helping... otherwise, it's just postponing the inevitable.
File under 'M' for 'Manic ranting'
I seem to remember some mass market minivan that had a fibreglass body... It's not an insurmountable problem.
Yes, they'll need to spend money to do it, but how is that different from any other R&D to advance your product? There are also other ways to improve efficiency, although they may not necessarily be cheaper. Hybrids, for example. There are also different kinds of hybrids. I believe some pickup truck models were using mechanical storage to recover energy from breaking or going downhill to improve mileage without the large cost of a battery-powered system.
And since this isn't even about improving the efficiency of any one car, but the average of the fleet, the average can be bumped up by discontinuing some of the lowest mileage vehicles. Phasing out huge SUVs like the hummer series helped, for example.
With the various new technology like better hybrids and fully electric vehicles this doesn't seem unreasonable. Even a fully gasoline powered vehicle that seats 4 could do this. There is a cost to consider in achieving this such that vehicles will need to be much lighter or more all electrics. Both of these cost more than you standard steel framed and skinned standard gasoline engine. Apart from making vehicles lighter you could also make them less powerful but people like zippy cars. Another thing that could be done is increasing the engine efficiency such as by using the Atkinson cycle increasing the compression (this would make it so people would need to use 89 or 91 octane instead of 87), or surface coatings to decrease internal friction. Additionally people are going to have to get use to seeing and using 0 weight oils (I have heard discussions of going to negative weight oil as well) instead of the standard 5w30. I am sure we are going to see some postings here about the magic devices that Detroit is sitting on that would produce 100+MPG on a big pig car, crap that is similar to fuel line magnets, or the infamous water power car.
Time to offend someone
The "Hydrogen Economy" is a scam. The cheapest way to make hydrogen is via hydrocarbon fractionation. Both green houses gasses will not be affected or reliance on fossil fuels.
putting the 'B' in LGBTQ+
The way the US dollar is going, you won't be able to afford "cheap" cars from China anyway. Yeah Bernanke harps on about how good a weak dollar is for exports. The US has always consumed more than it produces and the reality of the situation is that even Chinese crap is becoming expensive.
Seven puppies were harmed during the making of this post.
Which are great in some areas. But in other places, like the Great American Fly Over I live in they don't work in January.
putting the 'B' in LGBTQ+
The thing to realize is that going from 10 MPG to 20 MPG saves twice as much as going from 20 to 40.
That's a good point - it's better in general to use the inverse measure. It is blatantly obvious that going from 10 gallon/100miles to 5 gallon/100miles saves twice as much as going from 5 gallon/100miles to 2.5 gallon/100miles. In the first case the difference is 5 gallons and in the second it is 2.5 gallons - any fool can see it. This is the way they compare in Europe, and unlike pointless discussions about the metric system I think it is a much better standard for general use.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
Express it in amount per distance, it's easier to deal with. (It's also easier in daily life. People want to know how much fuel / money it will take to drive a certain distance, rather than how far they can drive with $20 of fuel.)
I'll use L/100km, as that's the normal measurement in metric countries (and what I'm more familiar with).
10 (miles per US gallon) = 24 litres per (100 km)
20 (miles per US gallon) = 12 litres per (100 km)
30 (miles per US gallon) = 8 litres per (100 km)
40 (miles per US gallon) = 6 litres per (100 km)
I think it's now clear. From 20mpg to 40mpg saves 6L, but from 10mpg to 20mpg saved 12L.
Hell, 20 years ago, a 1983 VW rabbit could get 54 mpg.
There are two types of people in the world: Those who crave closure
54.5 is pretty close
Compared to how the White House usually negotiates, that's amazing. I'm surprised they didn't do what they usually do: Give up concessions early, then compromise on everything the other side wants.
That's our life, the big wheel of shit. - The Fat Man, Blue Tango Salvage
Or you stop considering 2.6 litre engines to be the smallest anyone should put up with.
My car's got a 1.8 litre engine and by UK standards, that's pretty big. The average is more like 1.6; 1.3 and 1.0 engines are commonplace.
It also means that if they get exemptions for trucks/SUVs, that it will be largely meaningless.
They are getting the exemption; hence why Detroit loves this and several foreign manufacturers are calling it crap.
Yes, they'll need to spend money to do it, but how is that different from any other R&D to advance your product?
Parent nails the issue I feel. This world is full of corporations that act as if R&D is a waste. The business environment has changed so that once a company makes a profitable something, they act if they shouldn't have to continue to evolve and adapt. It is laziness and greed all wrapped up with lawyers, lobbyists and the never ending patent/trademark extension scam.
Aluminum has been used in the past on some vehicles but will increase the cost of the vehicle due to the increased material cost. Additionally aluminum is widely used in engine blocks with steel piston sleeves especially on higher performance vehicles as a weight saving measure, this also better balances the vehicle.
Time to offend someone
If I'm willing to pay the price of fuel, let me decide.
$789,062,132,241.
Your invoice is in the mail. When can we expect payment?
If I have been able to see further than others, it is because I bought a pair of binoculars.
Again, leaving Detroit in the dust. Innovation has always been the key to success... when did we get so tired of it?
It's always confirmation bias!
But in my head 20-40 also seems like twice as much.
The easy way to see is to pick a number of miles and see how many gallons it takes. So, for 12,000 miles, we have:
So, a jump from 10mpg to 20mpg save 600 gallons per year, while moving from 20mpg to 40mpg only saves 300 gallons. This assumes that miles traveled remain the same, but they don't. The number of miles traveled tends to increase when the fuel cost for a given trip is reduced, so actual savings won't be as much.
It also shows that other than reducing miles traveled, nothing can be done that saves as much fuel as increase from 10mpg to 20mpg.
Of course not... when my '93 Civic sedan manual was getting an average of over 35MPG (combined), what it makes you wonder is why it takes a hybrid to get that mileage now.
Stupid sexy Flanders.
The small airplane industry went through excessive legislation and lawsuits. The result was that people who wanted to fly an affordable small plane had to build their own.
It's not illegal to build your own car yet (most places). So people who want to drive a genuinely fun car with actual power and only 15 MPG will order a truckload of parts delivered. Several weekends with an air wrench and they'll have whatever they want.
People like you were probably heckling the Wright brothers, saying that heavier than air flight wasn't possible. Some things may not be "possible" today (like 1000mpg; if that ain't hyperbolie, I don't know what is), but 60mpg is well within the realm of possibility in the next 20 years.
I'm all for reducing government meddling (like repealing drug laws), but self-regulation is a myth in this day an age. Take the history of phosphates in detergents. When the government (rightly) forbid phosphates in laundry soap, many said that it was meddling, despite the fact that ground water was being polluted. Moving the goalposts, people then claimed it was impossible to make an effective laundry detergent without phosphates. Yet here we sit with clean clothes and clean groundwater. Wash, rinse, repeat (pun intended) for banning phosphates in dishwasher detergents.
The only thing stopping progress is big business, big money and entrenched interests. I have hope that human ingenuity (in the form of scientists and engineers; yes, educated people) will overcome. The day we really have to fear is when longevity allows regressive throwbacks to live forever and allows them to keep abusing control over those with less power than them.
Nathan's blog
Honda insight first edition was aluminum and dented if you looked at it funny.
Do not look at laser with remaining good eye.
I seem to remember some mass market minivan that had a fibreglass body... It's not an insurmountable problem.
That would be the Renault Espace. I don't know if it meets USDOT crash standards, tho.
Again, leaving Detroit in the dust. Innovation has always been the key to success... when did we get so tired of it?
When they figured out that bribes to politicians were cheaper than innovation? Just a guess.
Linux, you magnificent bastard, I read the fucking manual!
The Chevy Lumina and it's Olds counterpart. I had one in college and loved it. However, I did have someone back into the sliding door once. The small fist sized hole necessitated the replacement of the whole panel.
Honda is working on a home hydrogen fuel station that connects to your water main and somehow generates hydrogen from the water mains. Not sure how that is accomplished.
It's called electrolysis, it's not difficult to do. I was able to electrolyze water into oxygen and hydrogen in high school with some wire, a lantern battery, a discarded jelly jar, and some other odd items. The hard part is making it efficient and safe. Storing hydrogen is difficult on it's own. Because of these issues I don't expect this to become a household item for a very long time, if ever.
I am armed because I am free. I am free because I am armed.
It's the reason this will fail too.
EVERY automaker boss is thinking this right now: "54.5 is only the required average. That means I can still make gas guzzlers so long as there's some shitty little cars somewhere in the books that can do 100mpg. "
No sig today...
Laws/regulations are meant to control behavior. Taxes are meant to fund the government
Taxes can also fund government-sponsored efforts to discourage misbehavior. For example, taxing emissions funds clean air research. Taxing road use by individuals funds public transit infrastructure and research into telecommuting and remote monitoring. Taxing energy use funds efficiency research. Taxing energy imports funds wars to secure a friendly government where energy sources are mined (e.g. mid-east oil). When energy sources used by citizens are foreign, research into reducing energy use reduces foreign coercion of the citizens, something I guess even a libertarian might be able to get behind.
Unfairly punishing those who need to drive for work
Increasing road tax would lead to a rise in use of public transit and telecommuting.
For example, in my job I travel ~1/3 of the time, visiting sites all across the region to inspect the power system.
Increasing road tax would lead to a rise in use of remote monitoring.
They won't absorb the new tax, the consumers will.
Consumers will choose competing producers whose processes use less energy.
This means that urban and suburban areas will face increased food prices, for example, because there isn't enough farmland close to most cities.
The problem here isn't transport energy costs as much as zoning regulations that ban home gardening.
Do a test on a few coworkers. Don't ask an engineer who is going to write stuff on paper :)
Tell them to pretend that they have a pickup truck that gets 10MPG and a sedan that gets 20MPG. Ask them whether they are better off getting a high-efficiency 20MPG pickup or a 40MPG hybrid sedan to replace one or the other. Most people will pick the 40MPG sedan even though they'd save a lot more money by getting the new pickup.
If you phrase it as a 10GPHM pickup and a 5GPHM sedan upgrading to a 5GPHM pickup or a 2.5GPHM sedan people will more often make the right choice.
It's simple psychology... people see the 20MPG difference and think they are doing better than the 10MPG difference.
Since so many people live in two car households (commuter car and family car), I bet this choice gets made all the time. In fact, I just talked a woman out of replacing her Versa with a Leaf because when you do the math, replacing her fuel-sipping Nissan with an electric would never pay off, but replacing her old Explorer with just about anything would eventually pay off.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
That may be due to dissimilar metals. The aluminum exhaust heatshield on my Saturn fell loose because they used steel screws to mount it without using fiber washers at the contact points. They all corroded neatly around each screw head.
"He's lost in a 'floyd hole"
The EPA standards have been updated twice. That car would rate far less than 50 MPG today. Your anecdote is not reproducible, was not performed in a scientific manner, and the "knees-under chin" method of conveyance doesn't really meet with practical standards.
Gamingmuseum.com: Give your 3D accelerator a rest.
No it has been used on production vehicles. Here are a couple:
Honda Insight
BMW 3.0CSL
I could probably find some more for you but those are two that I know of off the top of my head.
Time to offend someone
When they were too big to fail
Time to offend someone
http://www.thedaily.com/page/2011/07/21/072111-opinions-column-cafe-dalmia-1-2/
"But to the extent that carmakers have complied with CAFE, it is less through radical innovation and more by simply slashing vehicle weight. In the 15 years after CAFE standards were first introduced in 1974, vehicle weight diminished by 23 percent. But every 100-pound weight reduction results in a 4.7 to 5.6 percent increase in the fatality rate. A 2002 National Academy of Sciences study concluded that CAFE's downsizing effect contributed to between 1,300 and 2,600 deaths in a single representative year, and to 10 times that many serious injuries."
I totally agree that the cars will have to be made incredibly light in order to meet the new standards. I don't agree that so many additional deaths are worth the savings in fuel. Given a choice, you could make a decision as to whether the increased risk of dying or being seriously injured in a car accident was worth the savings to your pocketbook and the environment. Here, there is no choice, the government has decided for you - you will increase your likelihood of dying in a car wreck because we say cars have to follow these standards.
Another important point, imo, from the same article:
"Sean McAlinden, chief economist at the Center for Automotive Research, notes that it is technologically impossible to squeeze anything beyond 45 mpg in fuel economy from current vehicles. That’s why Europe’s fuel economy has plateaued at that level, despite $8 per gallon gas. The 56-mpg-mandate will require a total, top-to-bottom overhaul of cars. Every part of a vehicle from its transmission to its engine would have to be replaced."
So, even with the large taxation on fuel in Europe, they can't seem to get current technology to perform at the levels needed by these standards. Now, what costs less for these companies (ie, better for the bottom line): To completely top-to-bottom overhaul their entire manufacturing systems and pour immense amounts of money into R&D, or to lobby the government to reduce the new standards? Want to guess which one will happen?
What? I think you have that backwards. Aluminum rusting due to salt? That aluminum ladder that is at the shore house in salt water for the last 15 years must be really special. It is in the salt water when in use. It is in the salt air 24 hours a day every day year round. We hose it off from time to time if the salt builds up on it.
Steel rusts out much faster then aluminum does. Aluminum gets that protective layer on it that stops corrosion.
I think they call that "having an MBA" around here.
Fanatically anti-fanatical
Wash the car really well before salting begins, and wax it really well with best wax you can get. Then just rinse it weekly, rarely better washing. Will help stopping the "public face" rusting very well.
Underneath the car apply whole bottom sprayable scratch/chipping protection (black stuff which makes hard surface). On top of that 5+mm thick underbody mass (recommended is min. 3mm thick). It's gooeye stuff, supposed never to dry 100%, black. Usually contains bitumen, pitch etc. Add to both a little bit of used engine oil (yes, i am serious) before applying.
Every year check underneath car if you need to add mass.
scratch/chipping protection and mass should be applied extra thick inside wheel wells and on skirts (both sides).
Why adding engine oil? Factories are denied from adding that nowadays, but it's the perfect protective agent! and adding a little bit (say 5-10% of volume) is not really a environment hazard at all, it was the factory pollution caused etc.
sprayable tar is very good for enclosures. Probably called simply enclosure protection, those meant for rust protection is mixed with some chemicals etc. and probably they blend it down too. Get tiny hose/straw meant for it, and you can spray it all the way within the enclosures :)
You'll need around 3-4 cans of chipping protection, 4-5 cans of underbody mass, 3 cans of enclosure protection per regular sized sedan.
If you have access to a car lift + compressor it's really easy & fast job with a spray gun meant for this job. Takes under an hour. Just wash the underbody really well first so there's no salt stuck on it, and let it dry completely first :)
What makes your car rust is tiny scratches etc. and the salt + water gets through to that to cause corrosion. Good layer of wax will help tremendously, along with really good paint job. The regular family sedan actually has kinda bad cheap paint job from factory, as the goals are cheap and good looking only. "Fleet" paint, meaning paint meant for professional use only vehicles, such as bulldozers, excavator etc. (There is also "fleet" paint for taxis etc.) is extremely well protective, and if you get your car repainted, i suggest using that.
surface rust sanding is not enough, that will not remove all the rust. You need a metal brush, or preferrably sand blast the rust from all the tiniest pores in the metal, after which zinc + aluminium undercoating (clean relly well with degreaser or otherwise it will not stick), then sanding primer (filler paint), putty/filler, sand it straight, filler paint, sand it even, basecoat, finish coat, clear coat. Why even apply clear coat? It will help in protection, albeit not necessary. If using "fleet paint", clear coat is quite useless tho as the paint is so thick and strong already.
Filler paint is filler which is sprayed like a paint but will provide a good base and cover all tiny speckles etc. doing all those steps, and especially the base well will ensure years to come rust free :)
Just sanding + basic primer + paint == Corroded within a year, guaranteed.
Sanding -> does not remove all rust
Basic Primer -> is not protective in any fashion, just to provide even color + basis where for paint to stick
Paint -> regular spray doesn't offer thick enough coating which would stick well enough, and many of them don't even "close" the surface, ie. humidity can pass straight through to the metal through paint and primer.
The conditions car surface have to endure are some damn hard conditions in areas where salting is obnoxiously heavy.
Oh, using filler is not only for looks, but it also helps to protect the metal under neath by providing a thick layer. It also helps for paint to stick etc.
(Yes, i own a bunch of old cars and they like to throw insane amounts of salt around here)
Pulsed Media Seedboxes
Aluminum doesn't rust, and it doesn't react with salt. They wouldn't make pans out of it if it did.
It corrodes. The reason why it's often not a problem is the way it corrodes - it produces a layer of Al2O3 (sapphire dust) that prevents the corrosion from going any deeper. But there are exceptions.
Contact with certain other metals with different electric potentials causes galvanic corrosion. An iron screw in an aluminium pan will cause it to corrode around the screw.
And every cook knows not to cover salty food made in an iron or steel pan with aluminium foil, because the galvanic differential combined with the salt will cause the aluminium to corrode very quickly, leaving not-so-healthy residue on the food, and holes in the foil.
The problem with aluminium corroding is the main reason why aluminium pans aren't very popular anymore, and even illegal some places (you consume parts of the corrosion over time, and there is a possible link between using aluminium pans and brain damage).
Also, mercury is killer for aluminium, as it will first react with the aluminium to form an amalgam, and then the aluminium will corrode, leaving the mercury free to start the process again. A single drop of mercury can quickly eat and spread through quite a large sheet of aluminium. Which is why mercury is on the verboten-list when flying.
What aren't they writing into regulations. A polition sees a cartoon of a piano falling from a tall building onto a car, and you get a bunch of new regulations. Do you know how much it costs to rent a piano and a tall building fot those tests alone? The Road Runner show created a lot of regulations about strapping rockets, and other things, onto your feet and slamming into busses. Honda has to build walking robots so they can test miniatures of their cars against giant alien robots. And now they're working on the Transformer movies.
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
It doesn't rust but it can corrode.
An excellent guess. Tucker was innovative but the big 3 stomped it out by leveraging their government servants.
http://en.wikipedia.org/wiki/1948_Tucker_Sedan
It's the reason this will fail too.
EVERY automaker boss is thinking this right now: "54.5 is only the required average. That means I can still make gas guzzlers so long as there's some shitty little cars somewhere in the books that can do 100mpg. "
No, every automaker boss in thinking, "this is more than 10 years from now, I will be retired with a golden parachute long before we even worry about this."
No matter where you go, there you are.
When we as a culture decided we'd rather focus our lives on trying to become sports stars, American Idols, or Hollywood stars rather than go into challenging technical careers.
It didn't help that the corporations took advantage of those who did go into technical careers with never-ending "crunch times", salary compression, unpaid overtime, etc.
I understand the need to get people away from gas guzzlers...I do...but how is raising taxes to make it prohibitively expensive to drive at all any different from using the government to just mandate better mileage from the auto makers?
The short answer is that mandated fuel economy standards mostly just affect automobiles. It doesn't affect consumer behavior in any other positive ways. Gasoline taxes have all sorts of interesting second order effects. For example Europe taxes fuel significantly more than the US does. This has over time resulted in significantly better public transportation (trains especially), less suburban sprawl, and widespread use of smaller more efficient automobiles. Higher gasoline taxes would arguably be among the best things we could possible do for the environment.
If your goal is simply to raise the fuel economy of automobiles, then there is little difference between the two approaches. But a fuel tax would do more and thus is arguably the better policy. To be honest though, it is something of an academic discussion because there is no possible way a gasoline tax of any significant size will be passed in our current political environment.