If Driving Over The Speed Limit, Stop Complaining About Gas Prices

A vehicle will use more fuel when traveling faster and at a higher rpm. However stating that all vehicles will use a specific amount of extra fuel for every 1 MPH is a false statement. Fuel use is dependent upon the make and model of the vehicle and how aerodynamic the vehicle is. I bet my Toyota Solara won't use as much extra fuel going 85 versus 55 as someone driving a big (not aerodynamic) large truck. The truck will require extra energy to overcome the greater wind resistance. My car is more aerodynamic and won't require as much energy to overcome the wind resistance traveling at a higher speed. I will use more fuel but it's not the stated specific amount some people like to quote that everyone will use.


I read an article in a local paper that stated the same thing. In fact for cars made more aerodynamic and made for faster speeds, the article stated the fuel use was only about 3 to 5 percent higher. If I'm in a hurry, I'd rather spend an extra dollar to get to my destination a half hour to hour earlier. It would save me fuel if those who want to go only 55 on the interstate try to stay on roads where the speed limit is 55 instead of 70. Traveling 55 on the interstate causes traffic congestion and when these people try to pass someone going even slower, they cause a lot of other drivers to hit their brakes and waste gas accelerating again. Of course I guess that's the American way. You can talk about how much gas you saved traveling only 55 mph on an interstate where the speed limit is 70 and you caused all kinds of traffic congestion and made countless other drivers hit their brakes, then reaccelerate wasting fuel in their vehicles. Then you're happy telling everyone how much you saved.

Originally posted by TheHunted
Actually there is nothing wrong with my math. Not all vehicles have the same size fuel tank. The less fuel economy for the vehicle the larger the tank.

For example I have an 85 Olds Delta 88 that gets 20 mpg but also has a 25 gallon tank. My Lesabre has one that is 15 gallons.

So I'm sure your friends vehicle may have a pretty decent size fuel tank. Am I wrong?

I was really trying to be a smart###, but you seem to have missed it anyways. You stated that for every mph over 65 you lose 1 mpg. This is a very simplistic way to look at it and it's not right. Using your method, a car that gets 20mpg will lose 1 mpg every mph over 65 so at 85mph it's now getting 0 miles per gallon.

I did some highway driving last night and paid attention to my tackometer. My car seems to coast at 2k rpms at around 72mph. Am I wrong in assuming rpms is what actually determines your mpg?

Why don't people understand that the main cause of the high gas prices is inflation? And because of the demand on oil they are able to be the first to adjust for the inflation? Sure there are other factors, but we've had supply and demand issues in the past as well and still the price never went up this much.

The price of oil goes down, so does the price of gold and other commodities. Is this just pure coincidence?

You can't spend a trillion dollars on a war printing up new money and not expect the prices of vital resources to compensate and go up. Correct me if I'm wrong here, but the price of oil has tripled. Have we suddenly lost 300% of oil supply?

I can't believe people don't realize this.

According to Lord Barrack Hussein Obama (The Messiah) His Majesty

1. Inflate your tires to the proper rate

2. Tune up your vehicle

3. We can save more on oil then all the offshore drilling or driling in ANWR

LMAO What a joke he is.

Sorry, had to add that in.

Driving the speed limit makes sense to me, why I do all the time now.

Yes, I drive a big Ford Truck wouldn't trade it for nothing.

If America would build more refineries and drill here now, we would see a collapse of gas prices.... PERIOD.

Let the tree hugging crowd eat dirt! We (America) can become energy Independent and stop making World policy regarding oil. (Middle East, Russia, etc.)

My name is VDOG.45 and I approve this message.

reply to post by TheHunted


Wow, great point! I have personally been frustrated as cars whip past me to suddenly break at the next red light, only to jackrabbit away from the light when it goes green. In the back of my mind, I have felt like every one of those idiots has been making my gas price higher.

I just never thought about using it as an argumentative point. Imagine the idiots speeding in huge suvs.... Jerks!

DocMoreau

so if they raise the prices to 8$ a gallon, we should drive at 35mph on the highway.


YOU SEE the gap in your logic.

College Education rules.

Originally posted by TheHunted
I'm not saying that sensible driving will solve the fuel crisis. I do believe that automobiles are number in consumption of oil. Drivers are pretty much giving away money to the oil tycoons. Why give them free money when we are the ones being ripped of.

Lets prove that our demand is not the reason for sky rocketing prices but is due to greed and power.

why not just use ethonal when you can and keep the money here at home, than sending it over seas. look at brazil they don't import 1 drop of oil they run on ethanol they are truly energy independent. they exportt all of there oil. the food crisis becuase of energy demands is false, because there are endless things to make ethanol out of , and also the oil and gas companies spent over 1 billion $ to stop this from coming to market.

I live in California and commute to work 30 minutes away and people have slowed down. I used to drive 80mph consistently before prices skyrocketed. Now down between 65-70mph. Also, coasting into stop lights a lot earlier, drafting when I can, and accelerating slower from a stop. Getting about 20-30% more miles out of each tank than before so it does help.

I've been driving this same route for 10 years now and the one thing I've noticed this year is the change in the habits of the highway patrol. When I used to go 80mph, there were only a couple spots on the road where I knew the CHPs liked to hide. It was simple to slow down right before these spots and then pick right back up. Now, they are changing their routines, using speed traps with multiple officers on the side of the road, and picking spots where the speed limit drops considerably or where there is a lack of visibility like when coming over a hill. It's obvious they have to do this because they are not catching as many people speeding, which means less money for the city or county. It costs the CHPs a lot of gas to patrol, so now they are sitting on the side of the road in tricky spots trying their best to nab someone not paying attention to a change in speed limit or an inadvertent acceleration due to coming downhill.

It makes me wonder how strict they are going to get as the price at the pump bites a little deeper. It wouldn't surprise me if 1mph over the limit will truly become a punishable offense someday.

reply to post by '___'eed


The logic is don't worry about $8.00 a gallon until it happens. Your speculation is another huge reason for the price of fuel. Let's talk about the price of fuel and how to use less of it today, when the time comes we will discuss that. So much for college education...

reply to post by crawgator406


Ethanol is being widely used here in the U.S for fuel. The problem with that is with the higher demand on corn, it raises the price of all corn or corn based products. Now you are raising the prices on food which more people depend on then gas. Also ethanol does not have a very good fuel economy..

reply to post by DocMoreau



Thanks for the agreement. Every time I'm on the road I see the ones that you speak of. They speed light to light for what? Just to stop and race to the next one. These are the same people that are saying "I'm so tired of the price of gas". Consume less you may see a difference in your wallet.

Originally posted by BlueTriangle

Originally posted by TheHunted
Actually there is nothing wrong with my math. Not all vehicles have the same size fuel tank. The less fuel economy for the vehicle the larger the tank.

For example I have an 85 Olds Delta 88 that gets 20 mpg but also has a 25 gallon tank. My Lesabre has one that is 15 gallons.

So I'm sure your friends vehicle may have a pretty decent size fuel tank. Am I wrong?

I was really trying to be a smart###, but you seem to have missed it anyways. You stated that for every mph over 65 you lose 1 mpg. This is a very simplistic way to look at it and it's not right. Using your method, a car that gets 20mpg will lose 1 mpg every mph over 65 so at 85mph it's now getting 0 miles per gallon.

I did some highway driving last night and paid attention to my tackometer. My car seems to coast at 2k rpms at around 72mph. Am I wrong in assuming rpms is what actually determines your mpg?

I agree that the formula can't work. My truck get 12.8 mpg. I have about a 25 gallon tank. So, if I'm running, oh, 80 mph, according to this I can't go any further than 25 miles because I'd be empty. I don't know about the 55 mpgs at 5500 rpms in the civic, but I do know that I've driven more than 25 miles at 80 mph and I still had plenty of gas.

Originally posted by TheHunted
reply to post by cautiouslypessimistic

 

I'm calling this one a hoax or that you are from a different unvierse with different laws of physics. The higher the Revolutions Per Minute means how fast your engine is turning. The faster the turn then the more energy required. In this case the energy being used is fuel.

Then there is the resistance of air. The faster you move the more air resistance there is. No matter the size of your vehicle or engine you cannot escape that. The force of this restance slows your vehicle down, so to maintain speed your engine requires more energy. Once again the energy used is fuel.

[edit on 15-8-2008 by TheHunted]

You can not believe me all you want, but until you either do the research or test it yourself, you will not understand that you are wrong.

Yes at higher rpm you use more fuel, but you are also covering an exponentially increased amount of distance. Therefore, until you pass the point of peak efficiency(which is different for every car), you gain mileage by increasing speed.

Now, you cant figure this all out by a simple math equation. Really the only way to do it is on a graph, with a line for fuel used and a line for distance traveled. When those lines converge, that is your peak efficiency. And in an efficient car, that will be at higher speeds. Now, driving in stop and go traffic changes things dramatically, so keep in mind I am only speaking of constant speed freeway travel.

Also, say you travel 30 miles at a constant 90 mph and then make another trip of 200 miles at a constant 90 mph. You will get noticably better mileage on the second trip, because you have a greater amount of distance to make up for the disporportionate amount of fuel used to accelerate to 90 mph.

Now, obviously there are infinate factors that will affect the exact numbers, from maintanance to tire inflation to quality of gas, but as a whole, you will see an increase in mileage.

I dont expect you to understand this. But it is the truth.

Vehicles that differ in design are going to produce varying results when driven at differing speeds and at different R.P.M.s. The trucks and S.U.V.s are going to suffer a greater loss in fuel consumption at higher road speeds due to poor aerodynamics, rolling resistance, and mechanical friction. They are troubled in stop and go driving by drive train and overall weight. Trucks are great vehicles to use for moving heavy loads efficiently but are not really designed to be driven without a load. The main reason for the popularity is that due to federal laws. Trucks are given a break on meeting the projected M.P.G. guidelines and therefore provide larger profits for the auto industry and oil companies. Technological advances in engine management systems, aerodynamics, engine designs and synthetic lubricants are making large contributions providing more efficient vehicles that will go farther on less fuel and still provide more horse power than the cars of the past. The one thing that is going in the wrong direction is the newer cars can weigh up to 20% more than cars that provided the same engine displacement and proportional size 25 years ago. This difference is even more pronounced in cars for the U.S. market due to crash testing and safety engineering. More than anything else, a change in the aggressive driving habits of a large portion of the people on the road would make the biggest change in fuel consumption and safety concerns.

reply to post by BRQuick



Your MPG is your overall fuel economy. It's not how many miles you will go on one full tank. So how does the math not work? Average of 12 mpg x 25 gallons = 300 miles. Where does my math go wrong?

reply to post by cautiouslypessimistic

Also, say you travel 30 miles at a constant 90 mph and then make another trip of 200 miles at a constant 90 mph. You will get noticably better mileage on the second trip, because you have a greater amount of distance to make up for the disporportionate amount of fuel used to accelerate to 90 mph.

This makes absolutely no sense. In both cases, you must accelerate up to 90mph so where is the gain in mileage if both cars go the same speed?

Originally posted by Evil Genius
reply to post by cautiouslypessimistic

 

Also, say you travel 30 miles at a constant 90 mph and then make another trip of 200 miles at a constant 90 mph. You will get noticably better mileage on the second trip, because you have a greater amount of distance to make up for the disporportionate amount of fuel used to accelerate to 90 mph.

This makes absolutely no sense. In both cases, you must accelerate up to 90mph so where is the gain in mileage if both cars go the same speed?

It makes perfect sense and, not to be rude, but I have to laugh at how far over everyone's head this topic is.

they are going the same speed over different distances, meaning the further you go at a more efficient speed, the higher your average mpg will be. Afterall, mpg is nothing more than an average, and if you get higher efficiency over a longer period of time, the average will raise.

Seems a lot of people on this board missed out on math.

Originally posted by TheHunted
reply to post by BRQuick

 

Your MPG is your overall fuel economy. It's not how many miles you will go on one full tank. So how does the math not work? Average of 12 mpg x 25 gallons = 300 miles. Where does my math go wrong?

As i said before your math is completely wrong. Every car has a different peak efficiency rate, therefore you cannot put an infantile math equation to it.

reply to post by cautiouslypessimistic


You have to provide some proof of this peak rate you speak of. I've provided facts with clear evidence that driving slower regardless of aerodynamics increases fuel economy.

reply to post by cautiouslypessimistic


So far all you have done is provided wacky claims that do not hold true with the laws of physics.