National speed limit pushed as gas saver

[AZXD]

Understood!
That was my give in to Etta.

"But I'll give in a little on this.
I'm still wondering why I can't purchase these."

Originally Posted by Frenchy

Comparing apples and oranges, AZXD...We have not been asked to sacrifice.

[Ride the Lightning]

Originally Posted by AZXD

Nice charts ... Can you explain your opinion that a car is screwed up if it gets better gas mileage at 70 than at 55.

That's not an opinion, it's a fact.

As I stated, mileage is basically what results from the increase in engine efficiency as the rpm nears the torque peak for a given throttle position versus the increase in drag from increased speed. In order to achieve higher mileage at 70 than at 55 you would have to do a few things that would make the vehicle unpleasant to drive.

First, the drag coefficient would have to be made extremely low so that drag would be lower for any given speed, but that's the easy part. Never mind that in doing so you will have created a body that has very little passenger room and even less cargo room. It will also not be very pleasing to the eye.

The next thing you would have to do is create an engine that creates a combination of torque and horsepower curves that allow a very rapid increase in engine efficiency over a very short rpm range, and will do so at an rpm that does not result in large friction losses or excess exhaust emissions. This is what is typically called a "peaky" engine. It makes very good numbers, but only during a very narrow rpm range and typically at elevated rpm. Elevated rpm really should be avoided if possible because there are also fricitonal losses inside the engine that increase exponentially with engine speed. What this means for the driver is that you have the choice of shifting constantly to keep the engine in an rpm range where it makes some power, or you can drive around with your foot on the floor all the time in an rpm range that won't do the job and results in less than stellar performance and quite possibly reduced reliablity and durability. Sounds fun to drive!

The third thing you would have to do is create a transmission with enough gears to keep the peaky POS engine you designed last week in its powerband where it can work efficinetly. Of course, this is just a band aid fix for a poor engine design, but it's what we have to do to create the illision that our engine is actually pretty good. Cars and trucks now days have actually started to do this because modern engines are looking more and more like those described above. Ever priced a service or rebuild on one of these modern transmissions? It ain't pretty!

So what we've done is create a car that's ugly (which from what I've seen on the roads the last few years really isn't a big deal any more), uncomfortable, won't carry anything, has an engine that doesn't perform, and a transmission that never knows for sure what gear to be in because there are too many choose from, and costs a lot more because of all the added complexity. Sounds like something a consumer would want to me.

[eric_t12]

this IDEA is well and good, cut the speed and it WILL (in probably 99% of cars) save fuel.




the problem has already been posted. there are people who regularly do 90 down the interstates, i doubt the new speed limits (since the old weren't being followed) will have a significant impact.


also - when has government regulation FIXED something? the last thing we need is a govt "war on oil prices"...


...THEY WILL NEVER GO DOWN AGAIN...

[Ride the Lightning]

Originally Posted by AZXD

Agreed .... We are talking about the collective use of federal powers to mandate change.

If we want to do that, it's already done. The cars we drive today have been designed by unconsidered federal powers to the point that the government almost tells us what to drive, we just get to choose passenger capacity and color. Emissions compliance, the illusion of safety, fuel "economy", etc. are all mandated by the government directly. It's what you don't see that is killing us. Do we really need more fuel efficient cars, or do we need more energy efficient cars? As I've said in other threads, it takes so much more energy to build the car from start to finish that the mileage doesn't really matter in the finished product. IF we could get the federal government to drop the emissions, safety, and fuel economy standards for cars we could all be driving cars that got much better mileage and cost a lot less, plus the carbon footprint would probably drop considerably instead of rocketing upwards the way we are told it would by the greens. The only reason the EPA has a job is because the greens don't understand how much the environment gets hurt by trying not to hurt it.

[Ride the Lightning]

Originally Posted by eric_t12

...THEY WILL NEVER GO DOWN AGAIN...

That's what they said in the 70's, then low and behold I could fill up in 1999 for 60 cents a gallon again. We'll find a way to shift our energy dependence outside of the automotive world again. The only thing holding that back is the attitude of the American people. 30 years ago I believe the people still had a sense of responsibility to their neighbor and to the nation. Now people are so selfish that they don't care about what would help anyone else and they are all living on credit anyway, so the added cost doesn't matter to them. If we all had to pay as we go we'd be a lot better off.

[eric_t12]

That's not an opinion, it's a fact.

its only a fact if that vehicle doesn't run more efficiently at 70 than 55.




some get better mileage at 60 than 55.

case in point. last night we drove 75 miles to SIoux Falls, SD.

my friend's car had the electronic fuel monitor. his car performed extremely well at 68 miles per hour, something like 26 miles to the gallon. anything more dropped the mileage and anything less did too, slightly.


the myriad of differences in vehicles, engines, trans, weight, drag, et nauseating cetera would make the 'fact' in this case a pretty fluid concept.

[eric_t12]

Originally Posted by Ride the Lightning

It's what you don't see that is killing us. Do we really need more fuel efficient cars, or do we need more energy efficient cars? As I've said in other threads, it takes so much more energy to build the car from start to finish that the mileage doesn't really matter in the finished product.

THAT is another key point, IMO.

[eric_t12]

That's what they said in the 70's, then low and behold I could fill up in 1999 for 60 cents a gallon again.

...when the eased regulations they went down again. i'm sure world supply/demand assisted in it, but my point was the last thing we need is more regulation.




it fixes nothing.

ETA: unless its regulation of the government. 1787 and 1776 were seemingly great indications of it, IMO.

[Ride the Lightning]

Originally Posted by eric_t12

its only a fact if that vehicle doesn't run more efficiently at 70 than 55.




some get better mileage at 60 than 55.

case in point. last night we drove 75 miles to SIoux Falls, SD.

my friend's car had the electronic fuel monitor. his car performed extremely well at 68 miles per hour, something like 26 miles to the gallon. anything more dropped the mileage and anything less did too, slightly.


the myriad of differences in vehicles, engines, trans, weight, drag, et nauseating cetera would make the 'fact' in this case a pretty fluid concept.

It's also a fact that every single car on the road gets better mileage at 100mph than they do at 0 mph.

Could you provide us with the lab data from your drive? Wind speed? Road grade? The phase of the planets? A statement of calibration of the fuel monitor? It doesn't take much to change the rules.

The fact remains that the overall fleet of vehicles in the nation would be better off at 55 than at 70.

[eric_t12]

i never said they wouldn't.

you are the one citing a 'fact' when its obvious that the 'facts' can change with the vehicle.

can you provide lab data? you explained the theory well earlier, but provided no lab data that i could decipher... i never said it was a 'fact' all vehicles would do better at 70 than 55, i just stated an obvious flaw in the concept of 'this speed = better than this speed'