Posted: Sat Jan 27, 2007 3:11 pm Post subject: History of Fuel Efficiency
If this has already been discussed in another thread, somebody please let me know. I came across some numbers this week that I thought were just astonishing.
Efficiency of the Ford Model T: 25 to 30 mpg. link
Average Fuel Efficiency of Cars sold in 2006: 21 mpg. link
Clearly what we've been told about newer cars being more efficient is bogus. Increasing fuel usage despite increasing vehicle efficiency is often stated as a validation of Jevon's paradox. This statistic makes me wonder if we're drawing wrong conclusions. _________________ "So while you sit and whistle Dixie with your money and your power.
I can hear the flowers a-growin in the rubble of the towers.
I hear leaders quit their lying
I hear babies quit their crying.
I hear soldiers quit their dying, one and all." - OCMS
Joined: Aug 07, 2005 Posts: 302 Location: Columbia, MO
Posted: Sat Jan 27, 2007 3:48 pm Post subject: Re: History of Fuel Efficiency
Don't have a link for you, but I have a 1963 Plymouth Valiant (170 ci 6 cyl - 3 spd manual) that gets 24-30 mpg. I'm making it into a light pickup - it should do a bit better that way.
Crash standards and power mania have added greatly to the weight of automobiles. Also, every auto sold today is unnecessarily powerful - a car shouldn't have to acheive 0-60 in less than 17 seconds or so. My Metro can do it in 13 seconds or so, and it is considered "underpowered". We will learn soon that simply having transportation is more important than it being quick.
We are without a doubt getting more torque and horsepower out of a gallon of gas these days. So our engineers haven't died off or gone to sleep, they've been hard at work making our vehicles as powerful as the EPA will allow because the market demands it.
"Additional torque and horsepower will make a car move faster." As true for an automobile marketeer as it is for an automobile engineer.
Sad but true; power is a safety feature when merging onto todays insane freeways.
edit:added comment 2nd edit:fixing my "chart" _________________ "He who makes no mistakes isn't trying hard enough" Genghis Khan
"Everyone here is bribed not to kill each other." foodnotlawns
Coinflation.com
Last edited by Aimrehtopyh on Sun Jan 28, 2007 1:40 am; edited 1 time in total
Posted: Sat Jan 27, 2007 5:33 pm Post subject: Re: History of Fuel Efficiency
Aimrehtopyh wrote:
We are without a doubt getting more torque and horsepower out of a gallon of gas these days.
Well, you'd sure figure that 80 years of engineering would have brought some improvements. My point was not that all automotive engineers are morons. My point was that everyone seems to think that cars are becoming more efficient over time. In fact they are on average less efficient than the Model T. The emphasis has been on torque and horsepower, i.e. making them faster. Claims of making them more efficient are half hearted at best. _________________ "So while you sit and whistle Dixie with your money and your power.
I can hear the flowers a-growin in the rubble of the towers.
I hear leaders quit their lying
I hear babies quit their crying.
I hear soldiers quit their dying, one and all." - OCMS
Joined: Sep 29, 2004 Posts: 2330 Location: Pennsylvania, USA
Posted: Sat Jan 27, 2007 5:47 pm Post subject: Re: History of Fuel Efficiency
Efficiency is a relative term. The model T could be compared to a modern econobox. The econobox will out accelerate it and achieve more than double the top speed and carry more load and finally, get better gas mileage.
The reason for the low average MPG; people prefer gas guzzlers. _________________ "That's the problem with mercy, kid... It just ain't professional" - Fast Eddie, The Color of Money
Posted: Sat Jan 27, 2007 8:32 pm Post subject: Re: History of Fuel Efficiency
Sorry Smallpox girl, I dont want to rain on your parade but what you are talking about is relative fuel efficiency of vehicles, not the fuel efficiency of the engine itself. As someone said, the engineers have not been sitting on their duffs all these years.
Engine fuel efficiency is typically measured as brake specific fuel consumption (bsfc) which is a measure of how much fuel (by weight) is required to produce 1 horsepower for 1 hour. This measure of efficiency has improved a great deal over the years although the upper limits are somewhat fixed. These limits are around .4 for diesels and ~ .5 for gasoline.
The biggest improvement in bsfc has been the operating range of the engine; previously maximum efficiency could only be acheived in narrow operating ranges. In other words modern engines are more efficent over a broader range of driving conditions than their predecessors.
One of the reasons the diesel gets better mileage is the fact its fuel is 25% denser than gasoline. This directly affects bsfc. since diesel fuel has more caloric energy by weight than gasoline. The upper limits of efficiency are probably near at hand unless some new materials are designed and used. Simply put, an awful lot of energy is wasted in cooling down the engine, and a lot of heat simply escapes in the tail pipe.
Your issue is mine btw; why do people feel the need to commute to work in 275 hp, 5000 lb SUV's?
It is a problem caused by unnecessary horepower and weight, not engine fuel efficiency, sorry.
Posted: Sat Jan 27, 2007 8:47 pm Post subject: Re: History of Fuel Efficiency
smallpoxgirl wrote:
Clearly what we've been told about newer cars being more efficient is bogus. Increasing fuel usage despite increasing vehicle efficiency is often stated as a validation of Jevon's paradox. This statistic makes me wonder if we're drawing wrong conclusions.
Nope. Just looking at the wrong data. Cars of the 70's got 10 to 15mpg. As fuel efficiency went up, miles driven increased.
_________________ A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel."
Live in Arizona? Check out: http://sustainablearizona.org and read my blog.
Posted: Sun Jan 28, 2007 2:46 am Post subject: Re: History of Fuel Efficiency
drew wrote:
Sorry Smallpox girl, I dont want to rain on your parade but what you are talking about is relative fuel efficiency of vehicles, not the fuel efficiency of the engine itself. As someone said, the engineers have not been sitting on their duffs all these years.
I didn't claim that the engineers were sitting on their duff. I claimed that they were not working on making cars more efficient. If they were, cars would obviously get more than 21 mpg because cars got 25+ mpg back in the 1920s. A Saturn V rocket is an engineering marvel, but it isn't a very fuel efficient form of travel.
Quote:
Engine fuel efficiency is typically measured as brake specific fuel consumption (bsfc) which is a measure of how much fuel (by weight) is required to produce 1 horsepower for 1 hour.
Yeah. Sorry. Human transportation needs are measured in miles. Fuel is measured in gallons. Fuel efficiency of transportation is measured in miles per gallon.
I bet the SR71 has great bsfc, but it's a heck of a wasteful way of getting to work.
Quote:
It is a problem caused by unnecessary horepower and weight, not engine fuel efficiency, sorry.
Did I say it was an engine problem? I don't think I did. What you said is exactly the point I was making. OBVIOUSLY, the engine in a Model T is primitive compared to the modern DOHC computer-controlled wiz bang. My point was that its pretty shocking that they have managed to design the rest of the car so wastefully that the fuel efficiency has actually fallen despite all the improvements in the engine.
Montequest wrote:
Nope. Just looking at the wrong data. Cars of the 70's got 10 to 15mpg. As fuel efficiency went up, miles driven increased.
I'm pretty familiar with the graph. The problem is that the graph starts in 1950. If you extended it back further to the left, you would find that fuel efficiency, instead of being an upslope would be V shaped. (high at the begining, low in the middle, coming back up towards the end.) Maybe it's legit to just cherry pick out '75 to '90 and say that fuel efficiency went up and so did fuel consumption. The picture would be the opposite at the other end of that graph. (Fuel efficiency falling and fuel usage going up) Maybe the two are unrelated. _________________ "So while you sit and whistle Dixie with your money and your power.
I can hear the flowers a-growin in the rubble of the towers.
I hear leaders quit their lying
I hear babies quit their crying.
I hear soldiers quit their dying, one and all." - OCMS
Posted: Sun Jan 28, 2007 7:01 am Post subject: Re: History of Fuel Efficiency
drew wrote:
Your issue is mine btw; why do people feel the need to commute to work in 275 hp, 5000 lb SUV's?
Drew
Today, 64.5 percent of adult Americans (about 127 million) are categorized as being overweight or obese.
In a few years they need trucks too move them ))
the reason is that us americans are governed by christian talibans, their only pleasure is eating.
Also Saudis are overweight, did you ever seen the average muslim women )
so fat chicks, awful
Posted: Sun Jan 28, 2007 7:18 am Post subject: Re: History of Fuel Efficiency
You can get good data on fuel consumption, efficiency, etc. by looking on various EPA pages or searching on CAFE (Corporate Average Fuel Economy). It's true that current cars get slightly less mileage than 20 years ago but that's market driven (don't get me started on how Congress has refused to increase the CAFE standards since 1985 or how the tests do not reflect real-world driving or how there's no teeth in the law).
It is simplistic, however, to compare old-fashioned cars to what's on the road today. Average speed was much lower, there were absolutely no emission controls and no safety equipment.
There's a lot of vehicles out there that get great fuel economy, but as someone mentioned, if you're driving 10X further - does it really matter? Until there's a real crunch or we start taxing carbon emissions not much will change.
Posted: Sun Jan 28, 2007 9:12 am Post subject: Re: History of Fuel Efficiency
smallpoxgirl wrote:
I'm pretty familiar with the graph. The problem is that the graph starts in 1950. If you extended it back further to the left, you would find that fuel efficiency, instead of being an upslope would be V shaped. (high at the begining, low in the middle, coming back up towards the end.) Maybe it's legit to just cherry pick out '75 to '90 and say that fuel efficiency went up and so did fuel consumption. The picture would be the opposite at the other end of that graph. (Fuel efficiency falling and fuel usage going up) Maybe the two are unrelated.
Quote:
I claimed that they were not working on making cars more efficient. If they were, cars would obviously get more than 21 mpg because cars got 25+ mpg back in the 1920s.
Like I said, you are looking at the wrong data. If you look backwards from 1950, you will see that cars got larger, heavier, more complex as they evolved from the Model T.
Put a comparable sized modern engine in a Model T and I guarantee you will get more than 25 mpg. Cars in the 1970's were muscle cars, big bodys, big engines, raw horsepower. They got anywhere from 10 to 15 mpg. Increases in engine efficiency and a reversal of that trend gives you the graph results.
SPG, I think you need to look more at horsepower/mass ratios/speed with regard to mpg. _________________ A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel."
Live in Arizona? Check out: http://sustainablearizona.org and read my blog.
Posted: Sun Jan 28, 2007 9:40 am Post subject: Re: History of Fuel Efficiency
smallpoxgirl wrote:
My point was that its pretty shocking that they have managed to design the rest of the car so wastefully that the fuel efficiency has actually fallen despite all the improvements in the engine.
They havent designed the car wastefully at all. Fuel economy has been simply not a priority. Despite this lack of concern, vehicle efficiency is up when one compares apples to apples.
There are 3 things overall that effect fuel economy, aside from the above mentioned bsfc. They are vehicle aerodynamic drag, mechanical friction (tires, transmission, etc), and vehicle weight.
A modern car is immensely more slippery than a car from 1970, and mechanical friction can't be lowered that much, so the cheif culprits for the poor economy we see today are excess weight and horsepower.
As for the latter, a small engine is more efficient than a large engine because it's typical operation is within the peak efficiency operating range more often than its larger counter part, and larger engines have more mechanical friction.
The weight issue is driven by clever marketing and sadly enough demand. Engineers could make the vehicle body out of aluminum or composites but we'd see the price of a new vehicle sky rocket. Steel is cheap, that is why it is used.
People want trucks and suv's, they weigh more because they are bigger. There are now more of them so proportionally cafe levels have dropped.
But, as I said earlier, when we compare apples to apples fuel economy is actually up.
What do you think the hiway mileage of a 1970 suburban is compared to a new one?
Wanna guess it gets about 5 mpg worse fuel ecomomy? An '83 4wd gets 14. A 2004 4wd gets 18.
Similarly compare a new Toyota Corrolla to a 1989 model. The new one gets 41 mpg, and I am positive the older one can't beat that since it gets 30.
Even the fabled corvette is better compared to its older siblings. 27 vs 25 despite being outrageously faster.
Sorry smallpox girl, again! The issue is caused by what people are choosing to drive, that is what is causing the drop in standards. They want bigger vehicles which are powerful and heavy. Something has to give in the equation so overall economy has to go.
Be glad the engineers have been doing their jobs or we'd be screwed even worse than we are now. Could you imagine if everyone was driving suv's with 1970 tech?
Btw, the new Corrola with 41 mpg has 170 hp. The 89 version has about 90 hp. The 89 is a smaller car too. All the vehicles I mentioned have more horsepower than their older siblings, and lower emmissions too.
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