Is the Speed Limit a Gas Saver?

Mass transit was killed by Detroit interests, passenger trains
and infrastructure is minimal. Lack of planning for alternate
transportation is why we are in a bind.

Well we were sucked in and now we have to pay the price.
Quit complaining and do something constructive about it.
As for you SUV, gas sucking drivers of behemoth trucks and
cars you deserve the 8-10 MPG efficiency.

Our love affair with the automobile will have to change sooner or later or it has to become more efficient as a tool.

I suggest we use energy wisely for pleasure, consolidate trips
and drive only when necessary. It is easier than you think.

it’s true. i usually make 350 miles to a tank. although not to practical, i can extend that mileage per tank to up to 450 miles. How? Windows up, 60mph, no A/C and following a semi.

C’mon, really? Still? So for all cars - Prius, Hummer, Tank - 55mph is a magic number? I have a feeling it may be better for some cars, worse for others.

I have read in BBC’s Top Gear magazine that having a somewhat consistent and high average speed actually saves more fuel rather than going at high speeds and having to slow down for slower cars. The logic behind this is that you waste energy braking when you need to slow down and travelling at high speeds will require you to do more of this.

This is rather evident when you’re driving 500 miles along France’s motorway. Having a good average speed of around 92Mph which is a real 88mph will only take you 2hrs and 50mins and only one stop at the gas station because if you cruise along, you can avoid braking and rather swerve around the slower cars impoving mileage while trying to floor it will take you 5hrs and 55mins because you need to top gas up twice from all that stopping and for getting caught with the highway patrol. The speed limit there is 130km/h (well this is france). 88mph is just over 140km/h.

To put it to American context, there shouldn’t be a need to alter the speed limit, just drive with a high average speed as possible along the speed limit and you won’t go wrong. Avoid braking when YOU CAN to avoid unneccessary loss of energy through heat.

Cheers

55 is an arbitrary value. It is the median acceptable speed where most vehicles proved to have the most gas efficiency. The other things to consider are tire pressure, acceleration, deceleration, excess weight of junk in the trunk and wind resistance.

There is a person that took a stock Honda Civic vehicle and with some minor body modifications and $400 got up to 70mpg.

I believe that we are on the verge of a collapse in the oil industry and we should all be preparing for it. Battery cells, hydrogen boosters, solar, and other alternatives need to be lobbied for.

This country should have heeded the warnings that the 1973 gas crunch so aptly proved that we are too dependent on foreign oil. Now we are paying for our own foot dragging. We need to follow in the footsteps of Argentina and move to sugar based ethanol as well as developing other sources rather than blindly listening to the oil industry barons say that nothing is wrong. We have been the frog in the pot of water that has been heating to boiling and have been oblivious to our own demise. Wake up and get out of the pot of hot water before it is too late!

This recommendation seems to be entirely absurd. If driving 55 MPH will save people gasoline then why not inform them and leave it at that. Of course many people already know this and they still choose to drive faster. Why should the choice of saving time versus saving money be taken from the individual and replaced by a decree.

As an aside, if human caused climate change is a problem and can be reversed or slowed then rising gas prices will act as an impetus for change in how we fulfill our transportation needs.

Is the Speed Limit a Gas Saver?

The 55 limit was just as effective as prohibition. It turned the average citizen into a habitual lawbreaker. Even today, most cops allow a ten mph “grace” over the limit which is a direct result of Nixon’s asinine law.

Education is what is needed. Motorists need to know that 60 MPH is their optimal speed for mileage. A speed limit law would be a giant leap backwards.

BTW, I get 42.2 mpg in my sixteen-year-old Tercel.

I adjusted my driving habits based on a an article on hyperdriving that I read. I still us 87 octane gasoline in my 2005 Chevy Mailbu Classic (4 cylinder). I will usually get 28 MGD with the AC running down here in the deep south. By easing up on my gas pedal and aiming my RPM’s to around 2000 (2400 if necessary), I have increased my gas mileage to 31.5 MPG with the AC running. This adds up to an extra 45 miles travel distance for the same tank of gas! Oh, I also never travel more than 4 miles per hour over the speed limit (it varies from 45 to 65 for my commute). Driving habits can definitely reduce how much you spend on gas. :)

55/60 it doesnt matter what matters is where you drive and then your speed. Think about the car sales adds (28 mpg highway) so the speed limits and gas useage is to the where you drive not the speed. If they want to end the 145 per barrel cost bring back the 100 mpg carb. The gas companies and the car makers dont want you to save money they want it period. The bike and the rail suggestions are valid. More cities need to develope systems of transportation that allow for bikes and rapid transit

Of course 55 MPH will save more than 60 MPH. But 40 MPH will save the most because air drag begins to build drastically after 40 MPH. Best solution is a very streamlined and light weight auto with an “energy recovery braking system”. That would get excellent gas mileage at even 60 MPH.

I think 60 MPH would be a decent speed limit and with the high cost of gas, most folks would drive 55 anyway but we could still get to our destination without getting so frustrated that we become dangerous.

I was an Economics student in the early 80’s, and one study we needed to review for class concerned the 55mph speed limit (for the exciting class of Economics of Energy - actually, it was kind of interesting, just like Law and Economics was…). This study did not just look at the fuel savings, but also looked at the costs of the limit. Specifically, time costs and the value of that time.

For most folks in the East (like me) or in urban areas, the value of the extra travel time was somewhat limited, and the lower speed limit kind of made sense. But for the folks who lived in the Midwest, they were screwed. The value of the fuel savings did not come close to the value of the extra time spent on the road. I believe for folks in Montana the cost over the time of the study (I don’t remember whether it was 1 or 3 years) was hundreds of millions of dollars. That was in early 80’s money and just Montana.

If the limit is discussed seriously (and not just a political hack’s election year gambit), I certainly hope they look at *all* the costs of a limit, not just the fuel savings.

that showed the 55 mph speed limit saved 167,000 barrels of oil a day, or 2 percent of the country’s highway fuel consumption, while avoiding up to 4,000 traffic deaths a year. Let’s see what some of my friend had Read the rest of this great posthere

Speed limit won’t make any difference to overall fuel consumption. Most motorheads will still drive 80 mph on the highway, no matter what the speed limit. What it WILL do is amount to increased revenue for local law enforcement, in the form of traffic fines. Always a plus for the pro-law advocates.

The last comment was exactly right , except for one place. SUV drivers do not deserve low economy, THEY DON’T DESERVE THEIR SUV. I most of the way believe that I can blame Large SUV’s for bad fuel prices Etc etc. We were at a local gas station and this guy was fueling up a 2009 Cadillac Escalade and it was running up the price to like 100.00 and i said, ‘I bet you have had that thing for 2 weeks and already make 275 stops at a gas station huh?”

When China has completed all its freeways and every Chinese has a car, we’ll go back to using horses because it’s cheaper. It’s environmentally friendly, too. We did it once–we can do it again. The technology is here today.

I don’t worry about the speed limit. I heard you can save as much as 30% of gas consumption by driving 50 mph instead of 60, so I started doing it. I haven’t made any precise measurement yet, but it sure seems like I’m getting more bang for the buck. When you think about, that’s like getting 30% off on gas or saving well over a dollar a gallon.

It’s not the fittest or the strongest that survive. It’s the most adaptable.

I drive a 2001 Subaru Outback H6 at 75 (on cruise control) on the freeway all the time. I get 20.5 - 21.5 MPG driving at this speed. Last spring I was over at Death Valley to take some wildflower pictures and the speed limit is 50MPH in the park. According to a friend the speed limit is heavely enforced so I drove 50MPH around there for two days. I got 34MPG driving at that speed and probably would have been more had I not been making frequent stops to take pictures.

If I were to drive 50MPH on California highways I would be the most hated driver in the state or dead or bored out of my mind. I’d probably fall asleep at the wheel. But lowering the speed llimit does conserve fuel.

I have a friend who thought rolling down the windows opposed to using the air conditioning saved fuel but we proved that theory to be wrong also. Auto aerodynamics go right out the window (so to speak) with the windows open.

The best gas “saver” I know is congress getting off their duff and letting us drill for oil off the continental shelf. Cuba is drilling almost in sight of the Florida keys. When are we going to wise up and understand that the demos want to rule us unconditionally.

If the speed limit is 65 and I drive exactly 65 miles I get there in one hour.
If the speed limit is 55 and I am driving a distance of 65 miles I will still have to drive to reach the additional 10 miles. Won’t I be using gas during that time ?

I can only talk from experience. I have a 2006 Ford Mustang GT and I have found that my car mileage improves when going up to 79 mph. At 80 mph is neutral. No gain no loss. After 80 and higher it will start to decrease his miles per gallon. The maximum it will obtain will be 26 mpg if I drive a long distance at 79 mph. If I drag race the car on every stop light it will go to low 13 mpg. Stop and go kills my mpg and slow drivers on the phone on the left line reduced my mpg and upset me very very much. To bad I can install a M60 vulcan gun to my car like a jet fighter. This way I will blast these idiots out of the highway. ( Just dreaming).

You want to save money, fuel, save the planet etc. Stop buying large SUV or minvan. One person just driving a large SUV for no other reason than his ego? Why do we need a minivan for our kids. Children are small and can fit in the back seat fine. My two childrens use to fit fine in my Toyota Celica, Mustangs, Camaro and all the small cars I had in the past. In a minivan they get out of the seat and walk inside the van like a school bus and when the van breaks hard or gets into an accident the bounce all around the van like pin balls. In a small car there is no pleace for them to go and they stay put. When they are teenages they do not want to be seing with their parents they rather walk. So why a minivan. So you can drive every kid in the neighborhood while their parents save money in gas at your expense. Let someone else do it.

When I up my cruise speed from 65 to 80, my mileage drops terribly from 30.8mpg to 28.5 or so mpg. That is on my 1998 BMW 328i. Your mileage may vary. I am terrified that the Al Gore police will take my car away and force me to buy a private jet like Al uses.

By the way, do you realize you are destroying the planet by exhaling CO2? I call on environmentalists to immediately commit suicide and donate their bodies to an organic farm to try to make up.

I came across MyGallons.com which is supposed to save you big bucks on gas. When the gas prices are a little lower on a certain day, you puchase gas in bulk on a card the site issues. The card can be used at any gas station. But after the $39.99 annual fee and the $2 per replenishment fee I’m not sure it will result in much savings.

Automobiles are now designed to get their best gas mileage between 55 and 70 MPH. I had a 67 Chrysler 300 with a huge four-barrel carburator that couldn’t get less than 18.88888 MPG on the road at 80 and 90 MPH. That, actually, was its best mileage. Right now I have a Chevy Prism that gets 37 MPG on the road at about 65 MPH. The 55 MPH idea about saving mileage is a low limit and was appropriate before fuel injection and all these electronic controls. In the mid-1950s my father was car pooling with a friend of his who bought a brand new Mercury Montclair with the biggest engine and huge four-barrel carb. This car got 85 miles to the gallon! After a lot of harassment by Ford the guy finally sold the car back to the Ford Motor Company for $10,000 and a new Lincoln. The oil companies want to make sure that they don’t loose out on their obscene profits. They squelched the 100-MPG carburator.

The thing with this that I have yet to see anyone post about is that every engin runs different. My car gets the best gas mileage at about 59MPH were my truck gets the best gas mileage at abut 52MPH.

How can they take into consideration of lowering the speed limit when not everyones car gets the same gas mileage or the best gas mileage at the same MPH.

I think if you go back and check your facts, When the 55 MPH speed limit was first introduced in the 70’s, cars were designed to cruise at 70 MPH. Those vehicles got lousy milage at 55. In the early 90’s when the speed limits were repealed, there were more than 10 years worth of vehicles on the roads that were designed for optimum performance at that lower speed limit.

It is all a factor of at what RPM range the engine reaches it’s optimum power to fuel consumtion effieciency, and then gearing the vehicle for it’s weight vs that optimum engine power-RPM performance range.

I have a few quick questions for those of you familiar with Physics:

1. How heavy is your vehicle?

2. What is the average number of miles you drive a day?

3. How does it take to drive that many miles on a good day?

4. Given that you accelerate in an efficient manner, how many horsepower-hours does physics tell us that you need to move a vehicle of that weight, that many miles, in that much time?

5. How much would that cost in electricity? (Hint: conversion from horsepower-hours to what hours at 100% efficiency is 746 watt-hours equates to a horsepower-hour. But after factoring battery charge and discharge efficiency, we will be doing good at 1 KwH = 1 HpH. Electricity cost vary, but a good average is 10 cents a KwH. Don’t forget that currently, electricity does not include the same excise taxes that are included in the cost of motor vehicle fuel, so watch out for states, that requre that your vehicle only be charged at properly taxed outlets. Also don’t forget that since relatively few electricity generation plants have been built over the last few decades, and that many areas are already struggling under the heavy demand from air-conditioning loads, what would, this kind of additional load do to the the overloaded electrical grid?)

6. How does your computations compare to the current cost of gasoline?

Despite the numbers you used above, take them with a grain of salt as what to expect under ideal conditions. Like the inflated gas milage figures of last decade, the actual numbers achieved will be less forgiving.

Exo

One point that is overlooked about the former speed limit of 55 mph is that was the legal limit only. That was not the actual average speed of cars. One reason the limit was changed back to 65 was that no one was driving 55. Everyone was driving 65 - 70 mph. Any claim that gas was saved because of the 55 limit is faulty as very few drive at that speed (just as few drive at 65 now…..)

Why 55MPH? Well, the typical Interstate speed is 70MPH. Reducing the speed to 55MPH would slow down to 78.6% of the previous speed. Since the wind resistance (force trying to slow you down) is proportional to the velocity cubed, .786x.786x.786 is darned close to .5, or 50%. In other words, the wind resistance is halved at 55 compared to 70.

I hate 55! Did not like it before, will not like it again, if it comes to it. On the other hand, I also hate $4/gal gas. I just would rather make that decision for myself instead of it being forced down my throat. Where’s my old fuzz-buster???

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I think the speed limit can be a real big gas saver.Because i drive a ford truck and this past weekend i took a trip to houston and i drove about 85 90 the whole way there and i got 16 miles to the gallon.and usally on hte high way i drive about 55 60 and only get 12.5 miles to the gallon…so i think the speed limit as a lot to do with gas saving so…..

p.s. dot but a truck get a car!!!!!!!!!

I agree, driving slower would save gas, but no one wants to drive slower or they would be already. All a change in the speed limit law will do is make more money off of speeding tickets. We will never slow down until there is no more gas.

I think it’s fine that those in the congested East should be forced to drive 55mph, but those in the West must drive faster simply to get somewhere in a day. I know that driving I95 in Virginia would be risky at 55 right now, you’d be obstructing traffic. I dislike unreasonably low speed limits. Traffic pretty much defines a safe speed - driving much over or under that speed leads to accidents.

I can recall years ago driving in NV. It was a straight road no traffic for miles, cruising at 90, seeing one car in the distance. It was a police car who eventually did a U-turn and eventually gave me a ticket for exceeding 55mph. What utter nonsense. Another national limit will ad more nonsense.

Funny thing, On flat land my Prius gets 53 miles per gallon at 55 mph, 49 miles per gallon at 60 mph and 45 mpg at 65 mph. Now if going 55 isn’t your style because that 8 mpg doesn’t stroke your ego so you seem like you’re going like hell just to get there 45 seconds ahead of me, here’s a simple proposition. Figure what the top speed limit is, stick your cruise control 5 mph less and see what constant speed gets you. On flat land at 60 mph the average mpg actually went up to 53. Smoothing out all those insane wolf pack throttle adjustments to get around slower traffic gives you an extra 3 mpg.

Oil Cartel Lovers of the world, Unite against people like us who don’t mind saving a little gasoline. Fight 55 mph with all your strength. It is a real ego booster to brag about how much petroleum you burn!

I dont think that it really helpsbecause they are just going to keep going up and there going to keep the speed limit the same.

I’m sure it does. I think staying at a more constant pace saves gas mileage. I recently drove to Atlanta from Jacksonville which is a 450 mile drive. On the way there I had to fill up again ( I used about 1 and 1/4 tank of gas…12 gal tank, 2001 stock 1.8l turbo jetta). On the way back it was late at night at I set the cruise control to 80mph and had a little over a 1/4 tank left when i returned.

I think this would be great idea, although I think people would not take it seriously and not abide by the rules, therefore cops would have to become really strict about it. They must give out tickets to everyone to let them know it is a serious issue. But this is definitely a very positive action if it were to happen.

From experience, I had an ‘83 Celica GTS. There were two instances of the best mileage that I had ever gotten on the car. Keep in mind that I couldn’t use 5th gear unless I was going 60 mph.

1. A friend was lugging the engine at 55 mph in 5th. I got 31mpg.
2. I took a road trip (San Jose to Oakland then south to a road that took me over to 101 and back to San Jose). I filled up before I left. When I arrived back in San Jose I needed gas. Highway speed around 80 mph (and no cops in sight). Again I got 31 mpg.

Normal driving in San Jose resulted in much lower gas mileage, especially the hour it took me to go 15 miles for my daily commute (except on Monday Mornings and Friday Evenings when it took an hour and a half).

My new Sienna with an automatic transmission has a 6th gear. I have no idea what speed I have to be going to get to it, but for a V6 it gets great gas mileage even with city driving and infrequent long trips (I telecommute). I even got 26 mpg in it which is factory stated highway mpg. Normally I get closer to 25 mpg.

Apparently, the Transportation Research Board has concluded in “A Decade of Experience” on page 176 that the old 55 mph limit saved only 0.18% of the fuel used back then. Given the current US daily oil consumption as a proxy (more than 20.6 million barrels per day or so at $150 per barrel), this would appear to save less than $6 million per day to the one or two hundred million drivers in the US.

Isn’t this only a savings of approximately 3 or 6 cents per driver per day?

However, the same above-mentioned report appears to state on page 123 that these same drivers spent an additional one billion hours of time driving per year, at the lower speed limit. This would appear to require about a minute per day per driver, on average, for a savings of only 3 to 6 cents worth of fuel. This is only a savings of about $2 worth of fuel saved per hour of additional time spent driving, or a savings of less than 0.016 gallons of oil per driver per day!

I don’t support that idea. Isn’t this dumb? And, won’t the damage to our economy from this wasted time be worse than the harm to the environment or our national security from such a tiny use of fuel?

Isn’t this just another idiotic proposal from the same politicians who cannot seem to do anything but make the economy worse with every new law passed? Isn’t this just another idiotic way to make it more expensive to hire employees in the US relative to our competition in the rest of the world?

Who cares about jobs.

The government would accomplish far more by mandating the inclusion of real-time fuel economy indicators in all new vehicles. This would allow us all to judge the best fuel-economy speed for our own vehicle as it is loaded. These things are available, should be on all cars.

To suggest that 55 is the best speed limit for all cars is simplistic at best.

I think you guys are doing a fine job saving all this gas for me by buying cars that use less fuel and driving a speed limit that I do on back roads. This is providing me with the extra fuel that you don’t use to power my hungry 14mpg Truck, which is an 2008 model by the way.

So keep up the good work, it helps me to keep guzzling the gas you guys think you are saving.