Gas Saving Tips - Fact or Fiction
#1
06-06-2008, 05:47 PM
Gas Saving Tips - Fact or Fiction
This topic is brought up all of the time and these are the tips that are usually given to fellow readers to increase MPG. Take from this what you want because I am sure people will argue these to the death.
Fill up when it's cool.
The claim: During warm weather, it's best to refuel in the early morning or late evening, when temperatures have dipped, because gas will be denser. The denser the gas, the better your fuel mileage.
False. Both Consumer Reports and Popular Mechanics have ruled this rumor false. Modern pumps are temperature-compensated to regulate fuel density, according to Popular Mechanics. Even if they weren't, gas temperatures typically remain stable all day, Consumer Reports writes, rendering the advantage of going out of your way to pump at a certain time negligible.
Air conditioning vs. open windows
The scenario: It's the dead of summer, and you're driving on the highway. With gas prices north of $4, however, you choose not to run the air conditioning because of the strain it will place on your gas tank. Driving with the windows open will help you conserve gas.
False. In this scenario, this line of logic would be false. There would be no savings from turning off the air conditioning because opening the windows would create drag, reducing the car's normal gas mileage. Consumer Reports tested the theory while driving a Toyota Camry at 65 miles per hour, and found that choosing air or windows didn't make a justifiable difference.
That's not to say that air conditioning is always the best option. The Department of Energy's website suggests that turning off the air conditioner may improve fuel economy when driving at speeds under 40 mph.
To idle, or not
The claim: If you need to run into your house to grab something, or if you're sitting in traffic for even a minute, it's best to turn off your car. It's more fuel efficient to restart the car than to leave the engine idling.
True. This one is true. Some might believe that restarting the car's engine wastes more fuel than letting it run, but modern fuel-injection technology allows already-warm engines to restart without burning gas, according to Popular Mechanics. Idling, however, can waste fuel.
Avoid filling up when you see a fuel truck
The claim: If you pull up to a gas station that is receiving a fuel delivery, don't use the pumps. The delivery stirs up sediment in the station's tank that could be pumped into your tank. Dirty fuel will hurt your gas mileage.
False. While a fuel delivery may stir up sediment that gathers in a station tank, both the gas station and the car have filters that will prevent sand or dirt from affecting your car's performance.
It's somewhat of a hold over fear dating back to when gas tanks were made of metal rather than fiberglass, said John Paul, AAA's Car Doctor, in an interview. Stations regularly test their fuel supply for quality, he said.
"If you're on 'E,' and the low fuel light's on, and the only station around is the one with the tanker, go, and get the gas," Paul said.
Best day of the week
The claim: Tuesday — or maybe you've heard Wednesday? — is the best day of the week to purchase gas because prices level midweek.
False. If this were true wouldn't everyone be doing it? There is no best day of the week to make a pit stop at the pump, or predict when prices will dip.
There are several websites, locally our own guide to gas prices in your area, and nationally, GasBuddy.com and AAA's Fuel Price Finder — that allow you to canvass your town's stations without driving around in search of the best deal.
Higher the grade of gas, better the fuel economy
The claim: Your car manual recommends regular gasoline, but buying premium gas will get you better gas mileage because of its higher quality.
False. While premium grade is a higher-quality gas, that doesn't mean your car necessarily needs it, according to Consumer Reports. Most cars are designed to run on regular gas, and many cars that recommend premium can also use regular because modern sensor systems automatically adjust to prevent engine knocking, a pinging noise caused by premature fuel ignition. Make sure you read your vehicle's manual before making any changes to the products you use.
Over-inflate your tires
The claim: Filling under-inflated tires to their recommended pressure is a proven way to improve fuel economy. Conventional wisdom would follow that filling the tires even further, to the maximum on the tires' pressure range, will only improve your gas mileage.
False. Inflating your tires beyond the recommended level will reduce the portion of the tire in contact with the road and the resistance between the tires and the road, but over-inflating them can make for a rocky ride. Popular Mechanics has also road tested this theory and concluded that the gas mileage doesn't improve.
The difference occurs when under-inflated tires are pumped to proper levels. In fact, the Department of Energy estimates that this simple fill up can improve your gas mileage by 3.3 percent.
Pump slowly
The claim: You will get more gas for your money if you set the nozzle to the slowest setting while you pump. More gas, and less air and vapors, will pass through the hose and into your tank.
False. There's no truth to this claim, according to John Paul, AAA's Car Doctor. Gas station systems are designed so that little air or fumes will take the place of the gas for which you're paying dearly. There is one perk to pumping slowly, according to Paul. "What that will do, the end result is you will get a fuller tank, but you're still paying for it."
A dirty air filter will cost you
The claim: If your air filter is dirty, your engine will receive less air, but burn the same amount of fuel, throwing off the car's air/fuel ratio and making the vehicle more inefficient.
False. While this was once true, modern engine technology now compensates for the problems a dirty air filter would create. Both Consumer Reports and Popular Mechanics agree that today's engines will inject exactly as much fuel as the engine needs, and will adjust to changes in the amount of air being received. However, regular car tuneups can't hurt.
Fill up when it's cool.
The claim: During warm weather, it's best to refuel in the early morning or late evening, when temperatures have dipped, because gas will be denser. The denser the gas, the better your fuel mileage.
False. Both Consumer Reports and Popular Mechanics have ruled this rumor false. Modern pumps are temperature-compensated to regulate fuel density, according to Popular Mechanics. Even if they weren't, gas temperatures typically remain stable all day, Consumer Reports writes, rendering the advantage of going out of your way to pump at a certain time negligible.
Air conditioning vs. open windows
The scenario: It's the dead of summer, and you're driving on the highway. With gas prices north of $4, however, you choose not to run the air conditioning because of the strain it will place on your gas tank. Driving with the windows open will help you conserve gas.
False. In this scenario, this line of logic would be false. There would be no savings from turning off the air conditioning because opening the windows would create drag, reducing the car's normal gas mileage. Consumer Reports tested the theory while driving a Toyota Camry at 65 miles per hour, and found that choosing air or windows didn't make a justifiable difference.
That's not to say that air conditioning is always the best option. The Department of Energy's website suggests that turning off the air conditioner may improve fuel economy when driving at speeds under 40 mph.
To idle, or not
The claim: If you need to run into your house to grab something, or if you're sitting in traffic for even a minute, it's best to turn off your car. It's more fuel efficient to restart the car than to leave the engine idling.
True. This one is true. Some might believe that restarting the car's engine wastes more fuel than letting it run, but modern fuel-injection technology allows already-warm engines to restart without burning gas, according to Popular Mechanics. Idling, however, can waste fuel.
Avoid filling up when you see a fuel truck
The claim: If you pull up to a gas station that is receiving a fuel delivery, don't use the pumps. The delivery stirs up sediment in the station's tank that could be pumped into your tank. Dirty fuel will hurt your gas mileage.
False. While a fuel delivery may stir up sediment that gathers in a station tank, both the gas station and the car have filters that will prevent sand or dirt from affecting your car's performance.
It's somewhat of a hold over fear dating back to when gas tanks were made of metal rather than fiberglass, said John Paul, AAA's Car Doctor, in an interview. Stations regularly test their fuel supply for quality, he said.
"If you're on 'E,' and the low fuel light's on, and the only station around is the one with the tanker, go, and get the gas," Paul said.
Best day of the week
The claim: Tuesday — or maybe you've heard Wednesday? — is the best day of the week to purchase gas because prices level midweek.
False. If this were true wouldn't everyone be doing it? There is no best day of the week to make a pit stop at the pump, or predict when prices will dip.
There are several websites, locally our own guide to gas prices in your area, and nationally, GasBuddy.com and AAA's Fuel Price Finder — that allow you to canvass your town's stations without driving around in search of the best deal.
Higher the grade of gas, better the fuel economy
The claim: Your car manual recommends regular gasoline, but buying premium gas will get you better gas mileage because of its higher quality.
False. While premium grade is a higher-quality gas, that doesn't mean your car necessarily needs it, according to Consumer Reports. Most cars are designed to run on regular gas, and many cars that recommend premium can also use regular because modern sensor systems automatically adjust to prevent engine knocking, a pinging noise caused by premature fuel ignition. Make sure you read your vehicle's manual before making any changes to the products you use.
Over-inflate your tires
The claim: Filling under-inflated tires to their recommended pressure is a proven way to improve fuel economy. Conventional wisdom would follow that filling the tires even further, to the maximum on the tires' pressure range, will only improve your gas mileage.
False. Inflating your tires beyond the recommended level will reduce the portion of the tire in contact with the road and the resistance between the tires and the road, but over-inflating them can make for a rocky ride. Popular Mechanics has also road tested this theory and concluded that the gas mileage doesn't improve.
The difference occurs when under-inflated tires are pumped to proper levels. In fact, the Department of Energy estimates that this simple fill up can improve your gas mileage by 3.3 percent.
Pump slowly
The claim: You will get more gas for your money if you set the nozzle to the slowest setting while you pump. More gas, and less air and vapors, will pass through the hose and into your tank.
False. There's no truth to this claim, according to John Paul, AAA's Car Doctor. Gas station systems are designed so that little air or fumes will take the place of the gas for which you're paying dearly. There is one perk to pumping slowly, according to Paul. "What that will do, the end result is you will get a fuller tank, but you're still paying for it."
A dirty air filter will cost you
The claim: If your air filter is dirty, your engine will receive less air, but burn the same amount of fuel, throwing off the car's air/fuel ratio and making the vehicle more inefficient.
False. While this was once true, modern engine technology now compensates for the problems a dirty air filter would create. Both Consumer Reports and Popular Mechanics agree that today's engines will inject exactly as much fuel as the engine needs, and will adjust to changes in the amount of air being received. However, regular car tuneups can't hurt.
#2
06-06-2008, 06:52 PM
My comments below
Air conditioning vs. open windows
The scenario: It's the dead of summer, and you're driving on the highway. With gas prices north of $4, however, you choose not to run the air conditioning because of the strain it will place on your gas tank. Driving with the windows open will help you conserve gas.
False. In this scenario, this line of logic would be false. There would be no savings from turning off the air conditioning because opening the windows would create drag, reducing the car's normal gas mileage. Consumer Reports tested the theory while driving a Toyota Camry at 65 miles per hour, and found that choosing air or windows didn't make a justifiable difference.
That's not to say that air conditioning is always the best option. The Department of Energy's website suggests that turning off the air conditioner may improve fuel economy when driving at speeds under 40 mph.
Said it before. Windows down on Fit below 65 will not make a measurable MPG change. A/C sucks MPG down like all get out.
Over-inflate your tires
The claim: Filling under-inflated tires to their recommended pressure is a proven way to improve fuel economy. Conventional wisdom would follow that filling the tires even further, to the maximum on the tires' pressure range, will only improve your gas mileage.
False. Inflating your tires beyond the recommended level will reduce the portion of the tire in contact with the road and the resistance between the tires and the road, but over-inflating them can make for a rocky ride. Popular Mechanics has also road tested this theory and concluded that the gas mileage doesn't improve.
The difference occurs when under-inflated tires are pumped to proper levels. In fact, the Department of Energy estimates that this simple fill up can improve your gas mileage by 3.3 percent.
I have seen better MPG with tires at 51psi on my Fit
A dirty air filter will cost you
The claim: If your air filter is dirty, your engine will receive less air, but burn the same amount of fuel, throwing off the car's air/fuel ratio and making the vehicle more inefficient.
False. While this was once true, modern engine technology now compensates for the problems a dirty air filter would create. Both Consumer Reports and Popular Mechanics agree that today's engines will inject exactly as much fuel as the engine needs, and will adjust to changes in the amount of air being received. However, regular car tuneups can't hurt.
Run with dirty filter is BS. Keep it clean
#3
06-06-2008, 07:26 PM
i agree with you on the windows down and i prefer windows down over AC. also with the air filter cleaner filter is always a good thing, who would want to run with a dirty filter anyways?
#4
06-07-2008, 12:15 AM
I prefer the windows down as well. I usually don't roll them up until I am over 60MPH.
Also, I would never run with a dirty ass filter. And I hope that it is a common sense statement above and that they are not referring to a ridiculously dirty filter. Either way, I think that the majority of the stuff is true.
I have been running with my tires over inflated and my gas mileage fluctuates quite a bit. On top of that, my last two tanks of fuel have produced around 30MPG when I average close to 40.
Also, I would never run with a dirty ass filter. And I hope that it is a common sense statement above and that they are not referring to a ridiculously dirty filter. Either way, I think that the majority of the stuff is true.
I have been running with my tires over inflated and my gas mileage fluctuates quite a bit. On top of that, my last two tanks of fuel have produced around 30MPG when I average close to 40.
#5
06-07-2008, 01:01 AM
Over inflating your tires is just not smart, you are increasing the likely hood of a blow out. Remember air expands as temperatures increase.
For every 10 degrees change in temperature, tire air pressure changes 1 psi.
For every 10 degrees change in temperature, tire air pressure changes 1 psi.
#7
06-07-2008, 11:43 AM
im measuring how many miles i can get right now with the a/c turned on
in warmer weather. will see in a few weeks. need to repeat it several
times, but i can tell you that with the a/c on the mpg looks like it's taking
quite a bit of a hit. loosing probably 5-6mpg(?) vs without the a/c on
often.
primary reason is that the car is that much slower with the a/c running
so i force the car to go as fast as it did before. i dont really care about
mpg that much, (if i get over 30mpg im happy at this point) but just want
to see what im getting in real world conditions.
in warmer weather. will see in a few weeks. need to repeat it several
times, but i can tell you that with the a/c on the mpg looks like it's taking
quite a bit of a hit. loosing probably 5-6mpg(?) vs without the a/c on
often.
primary reason is that the car is that much slower with the a/c running
so i force the car to go as fast as it did before. i dont really care about
mpg that much, (if i get over 30mpg im happy at this point) but just want
to see what im getting in real world conditions.
#8
06-07-2008, 12:43 PM
Very nice Post! I like how you have put in credible references for each myth or fact. +1 Rep for you! 
#9
06-07-2008, 06:08 PM
Over-inflate your tires
The claim: Filling under-inflated tires to their recommended pressure is a proven way to improve fuel economy. Conventional wisdom would follow that filling the tires even further, to the maximum on the tires' pressure range, will only improve your gas mileage.
False. Inflating your tires beyond the recommended level will reduce the portion of the tire in contact with the road and the resistance between the tires and the road, but over-inflating them can make for a rocky ride. Popular Mechanics has also road tested this theory and concluded that the gas mileage doesn't improve.
The difference occurs when under-inflated tires are pumped to proper levels. In fact, the Department of Energy estimates that this simple fill up can improve your gas mileage by 3.3 percent.
And the debate rages on.
#10
06-07-2008, 06:38 PM
I'm satisfied from personal experience that raising my tire pressure from 35 to 42 has decreased rolling resistance. The car coasts longer and takes more pedal pressure to brake. This car is efficient enough to benefit from lower rolling resistance.
My suzuki samurai got 24 mpg no matter what tire pressure I ran at. I had a leaky valve stem and ran one front tire at 10 psi for a while. Never noticed because the truck(?) was so light and the least efficient part on the car was the crappy ECU controlled carb.
My suzuki samurai got 24 mpg no matter what tire pressure I ran at. I had a leaky valve stem and ran one front tire at 10 psi for a while. Never noticed because the truck(?) was so light and the least efficient part on the car was the crappy ECU controlled carb.
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