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54.5 MPG Comes With Trade-Offs

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akwaman
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Re: So why is reducing oil consumption, worth killing people?
akwaman   9/18/2012 8:47:49 AM
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Since I have been on vacation, Totally_Lost is arguing by himeself, and still making the lame point that CAFE standards kill and making excuses (lame ones) for the auto manufacturers.  Weak statement by Totally_Lost: "Since down sizing remains the most likely source of CAFE fuel economy gains...".  I hope that the engineers reading this publication are not so inept at finding better solutions than Totally_Lost.  The whole problem is that auto manufacturers would rather spend countless millions of dollars on fighting a standard, that they eventually reached, while making cars BIGGER and HEAVIER overall.  The statistics just do not agree with the assessment of Totally_Lost.  Let's stop making excuses for the auto manufacturers, and force them to step up and hire more engineers and less lawyers.  If the money spent on fighting CAFE standards were spent on finding solutions, we wouldn't have to set standards, AND the employment problem would be far smaller.  It's a game of smoke-and-mirrors, people like Totally_Lost help make excuses for the manufacturers, and they said in the 70's that the 27 mpg CAFE standard couldn't be met, but THEY DID IT, and now the average is over 28mpg.  If you want to believe people that say it can't be done (54mpg), you should NOT be an engineer... you are a defeatest and you should go flip some burgers.  The reality is that when it comes to safety, we have standards for that too, but some just refuse to use their brains and instead make excuses.  With that mentality, we will stay in the dark ages of denial and fear. Typical smoke and mirrors strategy,  like putting a 30 year old picture on your blog to make you look young and fresh, when your message is old and out-dated.

Charles Murray
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Blogger
Re: Question to Editor - More efficient options not in US
Charles Murray   9/17/2012 6:35:03 PM
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I'm sorry I didn't respond to your question earlier, PeterC1. Unfortunately, I can give only a partial answer. As far as the gasoline-versus-gasoline engines, I believe the differences in availability stem from from marketing, rather than technical issues. If there is a technical reason for this, maybe one of our readers can weigh in. In your question, however, you bring up diesel availability, and here, there is a indeed technical/political reason. Diesel engines will add between 25-30% in fuel economy, yet they are much more available in Europe than here. One reason for this is that you have to refine more crude to get the long-chain hydrocarbons needed for a diesel's low auto-ignition temperature. Because it's easier to break the crude up into lighter hydrocarbons than it is to create long-chain hydrocarbons, the fuel is harder to make. And that leads to our second issue: In a diesel engine you have to control fuel very precisely (whereas in gasoline engines, it's more about controlling air). The result is that diesel needs better control systems. Manufacturers say the rule of thumb is that an entry-level diesel engine will cost the manufacturer twice what a base gasoline engine costs to make. In Europe, they've dealt with these by problems by mounting a real push for diesel. There are incentives on fuel prices and I believe there are tax incentives (again, maybe our readers know more about the incentives). The bottom line is that diesels are wonderful engines and Euopean countries are getting a fuel efficiency benefit from them. To me, it seems more doable and logical than pushing battery-electric (i.e., pure electrics, not hybrids) cars, largely because the technology is here today, and appeals to a broader swath of car-buyers.

Totally_Lost
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Silver
So why is reducing oil consumption, worth killing people?
Totally_Lost   9/9/2012 12:14:40 PM
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Since down sizing remains the most likely source of CAFE fuel economy gains, why is killing people in smaller unsafe cars an acceptable option to reduce fuel consumption?

Even at the current CAFE standards, some car companies are choosing to produce safe cars, and paid nearly a billion dollars in the CAFE fines as a tax to maintain their high standards of safety. http://www.nhtsa.gov/staticfiles/rulemaking/pdf/cafe/CAFE_fines_collected_summary.pdf

Read: http://www.amazon.com/Traffic-Safety-Leonard-Evans/dp/0975487108

Prior to the mid 1960s, the US had the world's safest traffic. By 2002 it had dropped from first to sixteenth place in deaths per registered vehicle, and from first to tenth place in deaths for the same distance of travel. Over 200,000 more Americans were killed in traffic than would have died if the US had matched the safety progress in such better performing countries as Britain, Canada, or Australia.

Totally_Lost
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Silver
Re: More than one way to skin a cat...
Totally_Lost   9/7/2012 12:17:48 PM
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@akwaman writes : "Question:  You complain about all the inefficiencies of hybrids when they go up a mountain.  Why don't you mention that going down the mountain at infinity mpg and charging the battery the entire time, puts the efficiency - off the scales - on the way down? (What goes up must come down...) "

Because fuel consumption for even a 1 mpg gas guzzlier can be made to zero, if you turn the engine off and let it coast down the hill.

That isn't rocket science, or even important, as most downhill runs are on long highway sections at speeds where the aerodynamic drag consumes most of the available Potential Energy (PE).  As a matter of highway design, this is critical so most cars will not have to ride the brakes all the way down.

For your Prius, which has a tiny battery pack with only about 600W-Hr usable because of SOC bounding limits, that translates into 600*3600=2160000 joules. PE in joules is mgh, where mass in kilograms (1500 for Prius+Driver+Fuel), gravity is 9.8, and height in meters. 2160000/(1500*9.8) = 146 meter change in grade assuming no other losses. That is nearly insigificant in the mountains where the elevation changes are an order of magnitude higher.

For a pure EV with a high efficiency motor/drive and large high capacity battery array, the numbers are better, and very usable for ski trips.  For the 386kg Aptera 2E with a 20KWHr battery pack (72Mj), that is 72000000/(500*9.8) = 14693m or 48205ft of PE assuming no other losses, which is two orders of magnitude better than a Prius. In the real world, both Hybrids and EV's have other losses.

For short downhill runs in city/urban areas, at slower speeds, the motor generator efficiency is significantly lower.

Hybrids with motors that are 80% efficient, drive electronics that are 80% efficient, and battery systems that are 80% efficient, the ability to capture potential energy during long down hill runs is very limited .... 0.8 * 0.8 * 0.8 = 51% ... getting that 51% back into Kenetic energy(KE) has all the same losses, so only 0.51 * 0.51 = 25% of the original PE can be turned back into either PE or KE later. The rest turned into heat in the motor, drive electronics, and battery during the braking or later accelleration.

This is why I said that high efficiency air core designs like the CSIRO solar racing motor, where the Motor efficiency is 98%, with high efficiency drive electronics, and low loss battery systems,  makes a huge difference. 0.98 * 0.95 * 0.91 = 84% efficient ... allowing 0.84 * 0.84 =72% of the PE to be recovered as either PE or KE.

That for the math impaired, is 288% more efficient for regenerative braking efficiency.

In both cases above, I'm assuming the speeds and accelleration/decelleration rates are held in the optimal band of the motor/generator. If faster or slower operation, or accelleration/decelleration is required, then the efficiencies may be significantly lower.

Totally_Lost
User Rank
Silver
Re: More than one way to skin a cat...
Totally_Lost   9/7/2012 11:59:53 AM
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@akwaman writes: "I used data covering 40 years"

And I posted data that pointed out the deaths stopped dropping dramatically after the safety improvements following CAFE downsizing in the 1980's had all been implemented ... and have been relatively flat for the last 20 years. The fact is that roughly 40,000 people a year die, and that is just wrong.

And during that time every state has agressively adopted strict DUI enforcement, where in the 1970's many drunks were told to slow down and drive carefully, and sent on their way. Mothers Against Drunk Driving (MADD) founded in 1980 changed that during the 80's and 90's. Today, every major drinking holiday has agressive checkpoints deployed, which was enabled by a Supreme Court ruling led by MADD in 1990. http://www.madd.org/

Since DUI's were a significant factor in the majority of deaths, and remain so today, the agressive changes in DUI enforcement have made the single largest effect on automotive safety. The biggest change is 3 strikes laws, that take cars away from repeat drivers, and promote jail time after the 2nd offense.

Now the NASS database does have a DUI column, and that IS data you can check.

Totally_Lost
User Rank
Silver
Re: More than one way to skin a cat...
Totally_Lost   9/7/2012 11:51:39 AM
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@akwaman writes: "It has been proven, that making the ICE more efficient, and ignoring the other 3 factors you mention, can improve fuel economy."

Actually, making an ICE more efficient is part of "Drive Train Efficiency", as I previously discussed. ICE's today are highly optimal, nearing thermal efficiency limits (when you adjust for the other engine losses), that are hard limits. http://en.wikipedia.org/wiki/Thermal_efficiency

The new 2012 CAFE requires nearly doubling the fleet efficiency over it's term.

Gasoline ICE efficiency has been optimized for years, to the point that from 2012 forward, we are unlikely to see additional furture gasoline ICE efficiency improvements of more than 5-15% better than the best engines today. The best way improve efficiency is to switch the entire fleet to existing turbo diesel designs that are 30% more efficient than gas engines ... except for the problem that EPA regulations would have to relax NO3 emission limits. The new cleaner VW diesels are one good example. But we have a large group of environmentalists that hate diesels.

Currently heat and friction losses are the two largest efficiency issues, and with the exception of introducing ceramic based thermal barrier coatings (TBC) in the combustion chamber, they are pretty well optimized. Ceramics and Silicides are used in high performance engines, including some production cars, but they are expensive with only small increases in efficiency. An all ceramic engine is possible to seriously limit nearly all heat losses, but that technology would require a decade or more to mature.

Automotive fleet sizes/mass and aerodynamics have been optimized for years too.

There is a problem of diminising returns.

Either we abandon safety, or add electric motors and batteries to the design to create hybrids at a significant cost.

There isn't a free lunch here.

Totally_Lost
User Rank
Silver
Re: More than one way to skin a cat...
Totally_Lost   9/7/2012 11:35:48 AM
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@akwaman writes: "standards do not kill people, people kill people or themselves, the same way that guns don't kill people, people kill people.  If people didn't run into things, then nobody would get killed.  I think if you are concerned about safety, you would be trying to avert the causes of accidents and prevent the causes, rather than blame CAFE standard and think the problem will go away"

Your standards are way out of touch with our society.

Defective baby cribs that kill infants, are defective baby cribs. By your standard it would be the fault of who? By our standards we force a change in the design, so that kids do not die. The fact is that we finally forced drop down rail designs off the market, that were killing kids.

Defective toys that  kill children, are defective toys. By your standard it would be the fault of who? By our standards we force a change in the design, so that kids do not die from the toys. The fact is that we have forced hundreds of toys off the market that injure, choke and poison our kids.

Defective cars that kill children, are defective cars. By your standard the car isn't at fault. By our standards would should force a change in the design, so that kids do not die from being occupants in cars unnecessarily ... nor should their parents.

The point is that people are not perfect, and will make mistakes. When we design things that will kill them during common mistakes, we have failed as a society, if there were alternative designs that have significantly fewer deaths and injuries.

The entire work place safety regulations are built on this premise ... if you have three equipment design choices, choose the choice that will injure operators the least, and if possible, NEVER AT ALL.

Why do you belive saving a few barrels of oil is worth killing babies, kids, and their parents?

akwaman
User Rank
Gold
Re: More than one way to skin a cat...
akwaman   9/7/2012 11:35:00 AM
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I used data covering 40 years, including the 70's that you bring into question, and not just a set of data that fits your argument (It still doesn't fit your argument).  I'm not suprised that you would do that.  Even in your 20 year set of data, 14 years of the 20 were years that the % change of deaths was going down.!?  Better to look at the chart at the top of the page that shows the data relative to the population, than the data from the chart you took a sample set out of showing actual deaths, which still disagrees with your assumptions.

Totally_Lost
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Silver
Re: More than one way to skin a cat...
Totally_Lost   9/7/2012 11:23:55 AM
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@alwaman writes: "BTW, the overall trend of deaths due to automobile accidents has been decreasing for about 40 years, not 2 like you mention."

The facts are a bit different for the last 20 years:

Year    Deaths
1991    41,508  
1992    39,250  
1993    40,150  
1994    40,716  
1995    41,817  
1996    42,065  
1997    42,013  
1998    41,501  
1999    41,717  
2000    41,945  
2001    42,196  
2002    43,005  
2003    42,643  
2004    42,836  
2005    43,443  
2006    42,642  
2007    41,059  
2008    37,261  
2009    33,808                  
2010    32,885

Note that deaths have remained fairly constant until the economy crashed in the fall of 2008

akwaman
User Rank
Gold
More than one way to skin a cat...
akwaman   9/7/2012 10:47:18 AM
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No wildly pointing fingers, they were trained specifically on the real issues that cause accidents, standards do not kill people, people kill people or themselves, the same way that guns don't kill people, people kill people.  If people didn't run into things, then nobody would get killed.  I think if you are concerned about safety, you would be trying to avert the causes of accidents and prevent the causes, rather than blame CAFE standard and think the problem will go away if we allow the automotive industry to remain technologically stagnant and ignore the issue of limited oil supply and the stanglehold that it has on our society. Many people with kids, like myself won't put them in a really small car, it's common sense to protect your children, and if you ever tried to put a baby in a sub-compact, you know that that is not the car for a kid, for another reason... your back.  Thank you for your deep analysis of the important factors in fuel economy, but your argument only accounts for three factors, and ignores the engine size, efficiency, and power, which are integral parts of the equation and just as important, if not more so.  It has been proven, that making the ICE more efficient, and ignoring the other 3 factors you mention, can improve fuel economy.  It worries me that a guy a smart as you, Totally_Lost, would ignore so many factors, just to support the unsupportable notion that CAFE standards kill people, and the only way to reach CAFE standard is to make smaller unsafe cars. The evidence does not agree with that, because cars have been getting larger and heavier, for a long time and yet the CAFE standards ARE being successfully reached, fuel economy is going up, AND deaths on the roads are going down.  You are right that there are many reasons that the deaths are going down, the same way that there are many other reasons that the MPG ratings are going up, other than car size.

Here is one of YOUR ideas to increase MPG and not reduce size and weight: Your idea of adding a transmission to the hybrid to increase the efficiency, it would certainly help with elevation issues, but it can also help the efficiencies of all electrics (up to 15%).  Electric motors don't need transmissions as much as ICE, but with them you can reduce the size of the motor, and increase power and range.  Of course you add weight with a transmission, so they have to be lightweight.  This is exactly the kind of thing that when introduced will allow the CAFE standards to be met, without making cars smaller, along with a multitude of other tweeks to the ICE engine.  Here's one, that the industry is ready to adopt: Add stop/start technolgy on ALL cars, so we don't waste gas sitting at stop lights and traffic jams, this would also increase mpg ratings without reducing size, and save countless millions of gallons of gas.  The answer is not one thing only, it's many things, and getting rid of CAFE standards are not going to solve safety issues.

I have spent plenty of time in junkyards, but I will not be correlating crunched cars to their entries in the NASS database.  If you do that, you have way too much time on your hands.  Funny... I went to the site, and they let you search for cases according to a variety of accident causes, aggression, speed, drugs, alcohol...  I was looking for the field that allowed you to search for deaths caused by CAFE standards, and it wasn't an option... :)

Question:  You complain about all the inefficiencies of hybrids when they go up a mountain.  Why don't you mention that going down the mountain at infinity mpg and charging the battery the entire time, puts the efficiency - off the scales - on the way down? (What goes up must come down...)

BTW, the overall trend of deaths due to automobile accidents has been decreasing for about 40 years, not 2 like you mention. CAFE standards have been in place since the 70's.  I'm suprised that you haven't tried to make the correlation between the fact that cars are getting bigger and deaths going down.  Of course, with that fact, your theory of CAFE standards forcing the cars to be smaller would not hold water...

 

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