...curtail nonessential travel

[jtr1962]

BTW (also)... I noticed on my state highway this morning that I wasn't the only person going 55. Maybe other people heard "the call" and decided to help out too (whether the President will do his part or not).

From a transportation engineering standpoint I personally see slowing down to save fuel as merely a bandaid to compensate for horribly inefficient car designs. I'd much rather see government mandated maximum drag coefficients in the 0.15 or less range plus improved ULRR tires. These things would let you have your cake and eat it too, so to speak. That's where I would like to see us heading. A big part of the transportation equation is traffic flow efficiency (i.e. speed). We should be taking measures to allow us to increase legal speeds, especially on limited access highways, while at the same time using less energy than we do with today's cars even at 55 mph.

I know it may not sound like much, but on your 19 mile commute doing 100 mph instead of 55 mph saves over 9 minutes each way (assuming of course free-flowing traffic conditions all the way). People in this part of the country regularly complain when 2 minutes are added to train schedules for whatever reason. A few minutes each way is not an insignificant amount for a daily commuter even if it might be for you personally. Adding what amounts to many hours per year to people's commute time to save fuel is not the answer. Better vehicle design is. Another traffic engineering fact is that once you artificially try to slow traffic below it's "natural" speed, which is what the old 55 mph limit did, you end up with a breakdown in free-flowing conditions at lower traffic capacities. Or in layman's terms, it takes fewer cars on the road before you start having traffic jams (which of course shoot fuel economy all to hell). As a "bonus" you also end up with more accidents which use more fuel for rescue vehicles. I've read a few times that once these factors were considered the old 55 mph limit actually caused us to use more fuel rather than less. And I'm not even getting into the trillions of man-hours of lost productivity it cost us. Having an engineer spend an extra 10 or 20 minutes a day on the road doesn't strike me as good use of their time unless they're practicing for a second career as a taxi driver.

By all means let's push for alternative energy sources, more efficient vehicles, more use of public transportation, more telecommuting, less mechanized travel, and less nonessential travel. Those are all no brainers. However, forget the reduced speed limits. They didn't save fuel or do anything but cost the nation untold hours of lost productivity years ago. They won't do so today, either. If you want to make a personal choice to slow down you're free to, but I don't think that choice should be imposed upon everyone by legislative fiat, especially those already driving very efficient vehicles.

 

[gadget_lover]

I once thought as JTR did, that 55 wasted gas and lower speed limits caused congestion but I learned a bit about human nature after 35 years on the road.

Anyone who drives faster than their reflexes can handle is just asking for an accident. Put me in a car doing 85 on a crowded freeway and I'm frazzled at the end of the drive. That same drive at 55, where there is more tiem to react, and I'm fine.

Most of the traffic congestion areas I frequent is caused by too many cars. Period. The roads are as backed up now with 65mph speed limits as they were at 55. The difference is that people get to the traffic jam quicker. The jam itself is caused by many things, about 1/3 being bad engineering and the rest being driver error.

Engineering problems include many things. Some offramps can not handle the traffic load at business parks and so traffic backs up into the slow lane. Offramps and onramps are placed so close together that you end up with cars interweaving as one slows and the other accelerates and the traffic again backs up.

My favorite stupid driver trick is the ones who take an off ramp to get to the on ramp to avoid a slow down caused by cars merging from teh on ramp. Yes, they cause the problam they are avioding.

I've watched the gas guage many times, and 55 really does save a lot of gas in free moving traffic as compared to 70.

I won't even go into the .15 drag. My Prius is fairly slippery at .29. You won't get a family of 4 into a car with a .15 cd. If one was made long and thin enough, you'd not be able to park it.

Yes, a lower Cd is a good idea, but you have to bre reasonable.

Daniel

 

[powernoodle]

isn't this the same administration that gave huge tax breaks

Tax cuts are accomplished by the legislature, not the executive branch, and none of them (sadly) have been huge.

best regards

 

[Darell]

No car pooling in my plans. Here in my neck of the woods, if you're not doing at least 80-85 on I95, you'll get run over.

Yup. I used to say those same words... in reference to the same highway that I now drive 55-60 on. Six years of driving slower, and I still haven't been run over, nor have I impeded anybody in the other two or three lanes who wish to drive faster. :shrug:

Another point to add to the equation is how many accidents are *avoided* when people drive slower? And each avoided accident keeps the traffic flowing better, saving even more energy, yes?

 

[jtr1962]

I once thought as JTR did, that 55 wasted gas and lower speed limits caused congestion but I learned a bit about human nature after 35 years on the road.

Anyone who drives faster than their reflexes can handle is just asking for an accident. Put me in a car doing 85 on a crowded freeway and I'm frazzled at the end of the drive. That same drive at 55, where there is more tiem to react, and I'm fine.

You're talking about driving too fast for conditions (yes, I agree 85 on a crowded freeway is ridiculous) versus artificially slowing down to 55 in cases where it's safe and comfortable to drive much faster (i.e. on an Interstate with low to medium traffic).

I also agree that in the case of many/most commutes nowadays slowing to 55 mph is purely academic since traffic conditions seldom allow you to even reach the speed limit, let alone exceed it. I was watching local traffic flow speeds on the Weather Channel. For the most part during most of the day they didn't exceed 40 mph, and during rush hours were closer to 10 to 20 mph. Going even 55 mph under those conditions would be a plus, not a minus.

On the traffic jams, one thing I think would help immensely is building a visual barrier between the opposite directions of traffic. Nothing more frustrating to be stuck in a traffic jam only to find the cause is simply morons gawking at an accident on the other side of the road. Totally stupid behavoir and easily fixed with visual barriers (which also double as noise barriers).

I won't even go into the .15 drag. My Prius is fairly slippery at .29. You won't get a family of 4 into a car with a .15 cd. If one was made long and thin enough, you'd not be able to park it.

Yes, a lower Cd is a good idea, but you have to bre reasonable.

Ah, but once you go to EVs you can make the car a lot more streamlined just by virtue of eliminating the air intakes and making the bottom smooth. The EV1 I think had a Cd of 0.12 and it was perfectly driveable (or at least Darell never said it wasn't). If I recall you start running into some of the problems you mentioned once you get much below about 0.10 but I'd be perfectly happy if all cars fell between 0.10 and 0.15.

 

[270winchester]

On the weekend trips back home, I get about 26 mpg at 80mph during the day, that's why I prefer to drive at night now so there aren't too many people pressuring me to go fast. When I drove last time, a 90 mile drive including a major hill climb and the subsequent down-shift for the descent, I averaged 70 mph and 32 mile to the gallon....

That's why I bought my family work horse station wagon instead of a truck I always wanted...

I figured our boys in their hummers and Abrahms need the fuel more than I do....even if that means drivign a very non-descriptive Jap car...

Than again, with the skyrocketing fuel prices, I seriously hope all the people with large vehicles don't cause traffic congestions by going too slow to save gas....I ahve seen a few now, housewives who used to put the pedel to the medal in their Expeditions are now driving slower than my grandmother walking to the corner store...

We don't have to travel less, just drive normal and drive a car that's the right size for your needs, keep your tires aired up, and change your oil when it needs and keep the car efficient. It's not that big of a deal....

 

[gadget_lover]

Ah, but once you go to EVs you can make the car a lot more streamlined just by virtue of eliminating the air intakes and making the bottom smooth. The EV1 I think had a Cd of 0.12 and it was perfectly driveable (or at least Darell never said it wasn't). If I recall you start running into some of the problems you mentioned once you get much below about 0.10 but I'd be perfectly happy if all cars fell between 0.10 and 0.15.

The links I find show the EV1 drag was .195, not .12 Cd. That was per an engineer that worked on it. That's pretty good but it's still a two seater. Make it big enough to add a baby seat in the back and I doubt that the Cd will remain at .19.

Don't get me wrong, drag reduction is good, but drivability and ergonomics are important too.

Daniel

 

[Darell]

The links I find show the EV1 drag was .195, not .12 Cd. That was per an engineer that worked on it. That's pretty good but it's still a two seater. Make it big enough to add a baby seat in the back and I doubt that the Cd will remain at .19.

Getting off the subject here... a 4-seat EV1 prototype actually was created, and the Cd was slightly lower than the 2-seater, IIRC. The only significant difference was that the car was 18" longer.

picture

That isn't an artist's rendering. For those not familiar with the 2-seat EV1, it may not look like much, but this one seats four adults.

 

[IsaacHayes]

My car has a coefficient of drag of .33 where a corvette has .29, so that's not bad at all. .15 is a bit to low for anything practical. I mean if sports cars don't even get anywhere near that low, then forget about it!

Also, the ideal crusing speed for maximum fuel efficency is dependant on multiple factors, not just the slower the better. Engine RPM and gear ration at a given speed matters, as well as wind drag, and drivetrain/rotational mass etc. Take for instance my car, which has obnoxiously tall gears. (1st goes to 45, 2nd - 85, 3rd -?? 4th -??). My RPM at 75mph is 2100 RPMs. If I'm driving 55 the RPMs are even lower (I think 1500) and my car will bog on a hill and I'll keep giving it gas, until I've pressed down enough for it to down shift and then the RPMs shoot way up and I'm flying down the road. This constant downshift/upshift wastes gas, but if I go faster I don't have the problem at all. I can keep 70mph without shifting out of 4th on our hilly highways.

If my gears weren't so tall and far apart, then the RPMs at 55 would be a bit higher eliminating the need for downshifting, and when it did down shift it wouldn't be such a huge change in RPMs and throttle position, and throw you back in your seat.

If I were to drive 55mph regularly (and do it safely without drivers hitting the back of my car) I'd need to re-gear my transmission. Of course I can't do that like you could if you had an old RWD car... I really *hate* driving 55 for that reason.

BTW I agree if you can't re-act at the speeds you drive you have no business driving those speeds. Same goes for your vehicle. If you're SUV can't handle at 90-95mph they why are you passing me?! grr. I've rebuilt and upgraded the suspension on my car and it can make split second maneuvers at 100mph and look just as calm as a car doing them at 30mph. It reacts fast and stays calm and stable. But most cars out there don't act the same and aren't built for that kind of driving, weaving and bobbing between cars moving slower than them. Plus the drivers don't have any idea of how a car behaves when it goes out of control... Well I'm just rambling now.. Basically we all need to calm down in our rushed lives and that will help with fuel, and health!

 

[jtr1962]

The links I find show the EV1 drag was .195, not .12 Cd. That was per an engineer that worked on it. That's pretty good but it's still a two seater. Make it big enough to add a baby seat in the back and I doubt that the Cd will remain at .19.

Don't get me wrong, drag reduction is good, but drivability and ergonomics are important too.

I think you're right. I believe it was the GM Precept or something else that had a Cd around 0.12. I got the two mixed up. Nevertheless, I have seen pictures of concept cars with drag that low, and they look perfectly useable to me. If I recall, the Prius comes in at 0.26 although that's nitpicking. Change a few details, such as adding wheel well covers, smoothing the bottom, losing the grill (for a straight EV only of course), paying attention to a few other details, and maybe you could get that under 0.20 without changing the basic shape. All it takes is a few sharp edges to seriously disrupt the air flow. Also, round shapes like chassis components are horrible (my railroad hobby taught me that-this is why they avoid projecting handholds into the air flow on any railcars designed for higher speeds).

I really think a win-win situation here would be increased research on ways to sustain laminar flow. I vaguely remember something about an airplane wing using thousands of tiny holes (small air jets) to induce laminar flow. Besides that, there are also some shapes which inherently have partial laminar flow on their own. The beauty here is that you could end up with shapes where nothing at all is compromised, but which require far less energy to move. Extrapolating what was done with human-powered vehicles to a full-size sedan, for example, and it might be possible to sustain 65 mph using only 5 HP instead of the 15 to 30 most of today's vehicles require.

Maybe this belongs in the EV thread instead but I thought it was relevant since it has to do with saving energy.

 

[jtr1962]

If you're SUV can't handle at 90-95mph they why are you passing me?! grr.

I didn't even know most SUVs had enough power to reach those kinds of speeds given the boxy shape. I thought the majority of them had trouble breaking 80. Regardless, I dread to think of the fuel economy they're getting at those speeds (we're probably talking gallons per mile here ), to say nothing of the hazard they're creating due to their instability. Seriously, SUVs are so unstable and inefficient if I had my way I'd govern them to 45 mph. They are off-road vehicles, are they not? 45 mph is flying for off-road conditions.

 

[ikendu]

I believe it was the GM Precept or something else that had a Cd around 0.12.

Yup. It was the GM Precept; diesel-electric hybrid, gets 80 mpg.

The Cd was .16

http://www.popularmechanics.com/automotive/concept_cars/1267946.html?page=1&c=y

BTW...GM, Ford and Chrysler all built such prototypes in the late 90's under the Partnership for the Next Generation Vehicle (PNGV) program. We've spent about $1 billion of tax payer's money on the program. Where are the production cars?

I'm reminded of the last scene from Indiana Jones; where the ARK is being wheeled into this giant warehouse full of nailed shut boxes. I guess all three of these taxpayer funded prototypes are sitting in there.

 

[ikendu]

The folks in the Washington DC area haven't slowed down. Yesterday I took a trip on I-270, where the speed limit is 55 mph. I set the cruise control on 65, and most cars AND TRUCKS were passing and weaving around me. (No, I was not in the left lane.)

Paul

Gee.

I guess the President's message just isn't getting out... or people are just blowing it off. This is actually the second time that he's made such an appeal since Katrina.

 

[picard]

I walk or bike more often. I leave the car at home most of the time. I use the car only for work or grocery shopping. I use up only 35bucks of gas a week

 

[VidPro]

what is non essential driving, i thought that was called WALKING
i am on the same tank that i had before katrina, and as soon as the price drops to resonable again, i plan to fill it back up.
in the meantime, essential walking is a priority
it takes lots less time than one would think, to even get to the store 2 miles away. but for them who drive to the mailbox :-( i understand

 

[gadget_lover]

Yup. It was the GM Precept; diesel-electric hybrid, gets 80 mpg.

The Cd was .16

http://www.popularmechanics.com/automotive/concept_cars/1267946.html?page=1&c=y

BTW...GM, Ford and Chrysler all built such prototypes in the late 90's under the Partnership for the Next Generation Vehicle (PNGV) program. We've spent about $1 billion of tax payer's money on the program. Where are the production cars?

I'm reminded of the last scene from Indiana Jones; where the ARK is being wheeled into this giant warehouse full of nailed shut boxes. I guess all three of these taxpayer funded prototypes are sitting in there.

You have to love prototypes and the hype involved. In the case of the Precept, they used ultra high pressure tires and skimped on the padding in the seats to save weight. To quote the article, the ride was on the HARD side of FIRM. That's not a prototype of a production car, it's a proof of concept vehicle. The 80MPG that they touted was totally ignoring the city driving experience (and city milage too). You can tune most any car to do one thing well. Make it do everything well and you have a car ready for production.

The PNGV was not a research program as far as I can tell. It was a way to convince politicians that the fuel and emission standards needed to be eased so they would not have to improve things. It worked, seeing as how California dropped their zero emissions requirement.

I'd love to see the gov step up and require efficient cars. They can be made, and with almost no cost penalty. Toyota and Honda are already making them.,

Daniel

 

[Threepio]

I have cut back on my driving, and plan my trips to keep the routes shorter. One thing that is showing an immediate payback is the Scan-Gauge I bought a couple weeks ago. It plugs into the ODB2 port in my Focus, and gives a current MPG readout among many other readings. It has been fun, as well as useful.
Has anyone heard of using Acetone as a fuel additive? This site, http://www.lubedev.com/smartgas/ has some interesting claims. But is it safe, or true?
--Bob

 

[gadget_lover]

I have cut back on my driving, and plan my trips to keep the routes shorter. One thing that is showing an immediate payback is the Scan-Gauge I bought a couple weeks ago. It plugs into the ODB2 port in my Focus, and gives a current MPG readout among many other readings. It has been fun, as well as useful.
Has anyone heard of using Acetone as a fuel additive? This site, http://www.lubedev.com/smartgas/ has some interesting claims. But is it safe, or true?
--Bob

In many states it's illegal to add anything to gasoline. Period.

There are many reasons for this. The additive may eat through seals (acetone is a solvent), or it may damage other pollution control devices. Some additives clog or foul the oxygen sensor that helps regulate the fuel usage in the car. Others will raise temperatures and burn out the catalytic converter. Some will eat through the rubber hoses and cause a fire hazard. Others just evaporate out of the gas and end up airborn.

I noticed that the smartgas site articles that I purused had zero hard info about pollution. They did not address the impact of acetone on RTV or shellac'ed gaskets. I did not read the whole article. I usually stop when the "study" starts to quote other guys who have tried it with no known ill effects. That's the first sign that it's bogus.

I'd stay away from any additives. After all, if Shell could give you 30% better milage and thus steal the business from BP, don't you think they would do it? You bet your life they would.

EDIT: I just scanned other posts on smartgas... The guy is nuts (IMHO) The scan guage sounds neat and probably very valid.

Daniel

 

[pedalinbob]

Yes, I have been more thrifty lately.

I agree that we all need to try to do our part in conserving energy.
Our government and many public officials certainly can learn to conserve.

A couple of examples come to mind, such as Clinton's highly expensive haircut and the Clintons' unnecessary vacation trips around the globe.
Incredibly wasteful!

Almost forgot about Robert F. Kennedy (the big environmental activist) cruising about the country in private jets that use tons of fuel and spews greats amounts of pollution.

Bob

 

[Empath]

Bob, please take note that your post is about the inadequacies of the forum members, rather than about the topic itself. If you could reword your post in a manner that addresses your concern of "energy waste by governmental officials in general", without complaining about members of our forum, your post will much less likely be marked as the point the thread headed toward personal attacks.

Edit: Well done, Bob. :thumbsup: