Just curious, why would the trucking companies want to reduce the speed limit? Wouldn't that slow down the trucks and slow down business?

Well as my car is, and on my last 1300 mile road trip. Across some very flat and very straight, its best MPG came in at 77mph or 73mph according to Tom Tom.

I went 55 for 30 minutes to test it. And the double nickels you seem to be praising left me with a %20 decrease in fuel efficiency.

I fail to see the point in this. The ATA hardly needs to have a reduced speed limit imposed in order to achieve this reduction... They simply need to ask their drivers to slow down. Let those who don't care about their fuel economy continue what they are doing, and the truckers can do 65 in the meantime.

Unfortunately, I live smack in the middle of the western US, where states are 400 miles long, and I'm quite literally, thousands of miles away from any coast.

If Mr Warner wants Virginia to reduce its speed then let him talk to his governer. I believe each state should feel to set its own guidelines in this matter, and each do what's best for their citizenry.

In the same vein, if the American Trucking Association wants its truckers to drive 65 in the few states where 75 is the maximum, then tell them to so. Trucking companies can (and have) made that decision independently, just like some airlines haved reduced speeds.

Finally, I have to believe that reducing highway speed limits, again in the few states where 75 is the maximum, is (quite literally) a drop in the bucket compared to the fuel wasted in the cities and in daily commutes.

Where was Mr. Warner when the ridiculous 35 mpg CAFÉ fleet average by 2020 was proposed?

It really doesn't matter. While I would rather have the nation speed limit 30mph, I know they aren't going change speed limits anytime soon. But gas can only get more expensive since discoveries of oil have just about come to a halt, and most countries have peaked on their oil production now. Going 75, or even 65, will cost consumers too much at some point and they eventually make changes. That might be buying a hybrid, but that only delays the matter. I think in 5-10 years no one will be driving more than 55mph because it will cost too much for that convenience of time.

So someone else should sacrifice?

I agree with Michael that it should be a state's right; and not mandated by Congress.

Now if the Federal DOT were to threaten to reduce funding for highways in a state that needlessly allows faster speed limits...that too, in my opinion, would be appropriate.

I live in Montana. It is at least an hour at the very least (driving about 80) between all of the major cities. This talk of 30-35 mph national speed limit is insane. The answer is in the technology. Is it not odd that for nearly 100 years all cars get about the same crappy? mileage and then when the "oil crisis" gets serious we suddenly have cars being made that get 55 mpg?

Recyclican: That would be like me saying to you that you're free to make any choice you want.

But don't make the choice I want you to make, and I'll beat you over the head with a baseball bat.

So feel "free" to chose...

Hey *****, its idling while stuck in traffic that wastes the most gas, PERIOD.

How about fixing most of the stupid reasons why traffic jams exist, then reduce the speed limit, for a net REDUCTION in travel time AND gas usage.

Oh wait, that would take some time, thought, and (God forbid) behavior modification.

Oh well, guess that won't happen. :/

E.F.Burke: "Is it not odd that for nearly 100 years all cars get about the same crappy? mileage and then when the "oil crisis" gets serious we suddenly have cars being made that get 55 mpg?"
No, not really. There was little incentive to improve the efficiency. In countries with (artificially) high fuel prices the high mileage cars have been popular for much longer than in the USA.

Idling wastes a lot of fuel in cities....which is why British Columbia has an idling law.

Driving fast/faster/fastest uses little/more/most fuel - it's a progressive rate that is easily determined.

Current hybrids are a joke on the buying public, waste resources for marginal gains and won't have a secondary market with a dead battery pack that costs more than a basic used car. I should know, I have a Segway with a dead battery pack and no one wants it.

VW will have a city car out in 2 years that in the 2002 test car achieved 264 mpg.

If you live in the middle of nowhere you should stay out of this discussion. My mom lives in the middle of nowhere and I consider her exempt...although she could use a higher mileage truck. Hello Dodge, make them available!

Finally, I slowed down on the highway and I get some really odd looks from folks - in the past 7 months I've passed only one old crazy lady on my highway. I improved my hwy mileage 22% by driving and added 3 minutes to my commute - I drive a Suzuki Samurai with an '81 turbo'd TDI. 22% is a huge! uptick.

Remember when speed limits were lower and people drove slower? People up here drive 75 cuz the cops'll let you slide. Voluntary speed reductions are just not in our general nature.

@ Michael - Well, Teddy is one of my favorite U.S. Presidents. Speak softly...

In all seriousness, Congress would have an easier time convincing states to reduce their speed limits using an incentive versus a mandate. Don't worry, I'm not suggesting we a "No Highway Left Behind" policy.

It depends on the car.

Your gearbox, aerodynamics, and engine efficiency map make this a non-obvious problem.

I guarantee that an insight or civic has a different optimal speed than a scion xB or a Hummer H1.

What I would like to see is a graph of mpg vs. mph on the window of every car sold. It's not like this would be a difficult test to run.

==== writers response follows ====
Absolutely!

I have a hunch that if you ran a decibel meter in the cabin, with radio and any vent fans off, it would be a pretty good surrogate for mileage/velocity relationship: e.g. the noisier overall the ride is, the more the turbulence and friction overall, the worse the mileage.

Two comments on the comments:

1. Traffic in the cities has been reducing in the past year. Traffic in the Seattle area is the lowest I have seen since I moved here in 1993. People are combining trips, telecommuting, riding bikes, using motorcycles and mopeds, and generally doing anything they can to avoid buying petrol. There is a light rail that is opening next year, bus ridership is way up -- basically, folks in the city are doing their part.

In addition to what is happening in the city, it makes sense to do whatever we can to reduce petrol use everywhere. Reducing the speed limit will make a dramatic difference, regardless of whether you believe your car has better gas mileage at 73 miles per hour.

2. I can not help but mention, however, that your vehicle does NOT get better has mileage at 73, no matter what you are being told by some electronic do-hicky. The wind resistance pretty much guarantees that any speed above 60 mph is going to reduce your mileage. There has been numerous studies that have shown that your peek gas mileage happens at the lowest speed in your highest gear, which is likely in the 40mph range. No one is going to want to travel on a highway at 40mph, even if it would improve fuel economy dramatically. So, they are talking about less drastic steps. But, you can rest assured that your best gas mileage happens well below 50mph.

Lowering the speed limit will also reduce accidents and save lives. As accidents cause congestion, average travel times will decrease as well.

tom:

The lowest speed in my highest gear is *not* around 40. I have a 5 speed with a loooong 4th, putting my lowest speed in 5th a little over 70. I would also get better gas mileage at 70 than 60, because I need to be in 4th gear at higher rpms to go 60.

One easy solution to gas mileage is more gears. If you have more gears you can go a wider variety of speeds (and probably higher ones, too) without resorting to gas-guzzling high rpms.

Miles per Hour, Miles per Gallon. All important.
And.
What I'd like to see : Gallons Per Month, gpm. How about an advertising campaign around people reducing their gpm?

The biggest force on the highway is wind resistance and it goes up at a cubic rate when you increase the speed!

Unless your gearbox and motor happen to run best when you are expending that extra power needed to go the speed the car is designed for. Its a balance thing up to a certain point.

For example 5 mph faster can take 30% MORE power on some cars when going 65mph. Its cubic, so the drag at 30mph is not having much impact. Its quite likely that around 55mph you cross the threshold where over 50% of your power is just fighting the drag (wind resistance!) A brick shaped car may cross that 50% threshold at only 45mph...

Reducing your drag and surface area are BIG BIG things at highway speeds and trucks need to take notice and start looking more like airplane fuselage.

I like what Richard has to say!

Let's reduce our speed limit to save lives- humans, domestic, and wild animals.

Feeding 2 birds with one seed (pardon the vegan-ness of this, I can't help it)!

If you are going to flaunt your mpg, please put it in perspective and list your year, make, and model and any changes that may have been made to the car. If nothing else, we can all buy your magic 77mph high efficiency dream car.

That being said, I traveled from Kansas City to Columbus, Oh driving between 55 and 65 the entire way driving a 2004 Honda Civic 4dr manual transmission. I did the calculations by hand at every fill up (not using a fancy gadget other than a simple calculator) and got the following: 47 mpg at 55mph and 43 mpg at 65.

Lesson: Check your work. I seriously doubt you get better gas mileage at 77 (or anything over 60 for that matter) than you do at 55. If you did, for God's sake, tell me what car so I can be stupid fast and cool like you.

This is foolish & we've tried it before.

Slower speeds means everyone is on the road longer for each trip which means higher traffic density. Traffic accidents go up faster than traffic density. The last time they lowered the speed, deaths went up. When they raised the speed, deaths went back down. To this day, countries like Germany, Denmark, France, Finland with higher speed limits move more traffic with a lower death rate than the US.

Gas consumption depends on engine RPMs not wheel speed. Sit in your drive way and hold down the gas pedal and watch the engine suck down the fuel.

Stop & Go traffic is what kills mileage. That's why city MPG is so much worse than highway. Slower speeds means more stop & go traffic.

The best thing we can do is telecommute. The second best would be to walk or bike. The third best would be an electric train, etc.

How's this for a magic wand? Utah is switching state employees to 4 day work weeks. Instant 20% fuel savings, less traffic & more time with the family.

(very basic explanation)

Highest gear @ Lowest speed = Highest Fuel economy.

Any increase in engine rpm past that point is an increase in fuel consumption.

Please post your vehicle specs and or modifications in regards to being more fuel efficient @ 70+ mph.

At the very least model and year.

Congressional members want us to do 55 again ?
Why, to save their A__ on the gasoline crisis.
They (congress) did NOTHING for 30+ years about a energy plan. Then in the wake of their incomptence, they want US to slow down and save gas!!! Is that insane or what?
This November our mission is clear. Vote OUT ALL INCUMBENTS and push for term limits next year... Politicians are getting much to comfortable and have the mind set that they can do anything that benefits them or their particular party. You and I are no longer in the equation....enough is enough.

Phil Jenkins

You are the reason the republican party is in the shape it is in. YOUR IDEA IS SENSELESS AS ARE MOST OF YOUR POLICTCAL STANDS.