Frugal Living 

Five Gas Saving Myths

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Gas StationWith global turmoil continuing to threaten higher gas prices — especially with the summer driving season just around the corner — it is little surprise that many people are looking for ways to save money on gas.

Indeed, as gas moves toward the $4.00 per gallon level that many think is inevitable, increasing fuel economy becomes even more important. We want to be able get the most for our gas station dollar. It is tempting to believe that you can do a few simple things and then find yourself raking in the savings. The truth, though, is that some “conventional” wisdom about saving money on gas is outdated. Or even downright false. Here are five gas saving tips that probably won’t do much in terms of saving you money at the pump:

1. Add a “Special” Device to Your Fuel Line

If you look online, you can find any number of products that claim to improve your fuel efficiency. All you have to do is install some device in your fuel line or other part of your care, and then watch as the “miracle” saves you money. Unfortunately, few — if any — of these devices actually work. The Federal Trade Commission makes it clear that there are no “gas saving” devices endorsed by the government. Watch out, too, for false claims that EPA testing has been conducted and that the device has been “proven” effective.

2. Pour Additives into Your Gas Tank

On top of adding special devices to your car, there are some claims made that you can dump a bottle-full of some special fuel additive to increase your fuel efficiency, or clean the insides of your car to make it more efficient. Others claim that you can use oil additives to help increase fuel efficiency. It doesn’t appear that these additives are likely to help you any more than adding a special device to your car.

3. Switch Out Your Air Filter

It’s true that properly maintaining your car can help it run better and more efficiently in general. In the past, recommendations were made that changing your air filter could help matters. Ditto for a high performance filter. However, if this were true in the past, it isn’t now. Consumer Reports points out that computerized cars have other ways to compensate. Changing your air filter is unlikely to do much on its own. Instead, you will need to develop an overall habit of better car maintenance to get as much as you can for your money.

4. Fill Your Tank When The Air Temperature is Cooler

I remember being told that the best time to fill your gas tank is in the morning. The air temperature is colder, so fuel is denser. I remember someone telling me that warm air will help the gas expand later, so you get less taking up more room in your tank. The truth, though, is that it probably doesn’t matter enough to make an appreciable difference. In fact, think about where the gas is stored: Underground. It’s already at a cooler temperature — no matter how hot it is outside.

5. Don’t Turn Off the Car When Running Errands

It used to be that the conventional wisdom was that you should keep your car running if you were just running errands. Whether you were visiting the bank, or just chatting with a neighbor, turning off the car was a no-no. You might remember hearing that it took more gas to start your car than to just let it idle. Perhaps this was true in the past. However, the miracle we know as fuel injection has changed things. Idling your car really does use up more gas than starting it. It’s also a myth that modern cars need to “warm-up” for a few minutes before driving them in winter.

What gas saving myths are you surprised that people believe?


{ 47 comments, please add your thoughts now! }

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47 Responses to “Five Gas Saving Myths”

  1. SoonerNATX says:

    i’ve known people to shift into neutral when coasting to a stop. although it’s not a myth (probably more of a myth nowadays due to advances in trannies)… however i do believe that the amount you would save by shifting will be offset by the wear you add to your tranny.

    another one is rolling with the windows down instead of the a/c on. although the a/c is parasitic of power… its not so much when compared to having the windows rolled down (at high speeds, of course)

    • Chuck says:

      Many modern cars shut off the fuel injectors completely when you are engine braking (since the fuel is not needed to keep the engine spinning). When you shift into neutral (or press the clutch) fuel is needed to keep the engine idling. So it’s likely that shifting into neutral will cause you to burn more gas (and brakes). I think transmission wear is a myth, too.

      • Amy Saves says:

        I shift to neutral when I’m at a red light. I heard it’s better than staying in D.

        I’m confused.. is it better to leave in in D?

        • SoonerNATX says:

          i used to shift (mainly on flat surfaces so i wouldnt have to hold the brake) but then realized that my car idled faster when NOT in gear… so i stopped. higher rpms = higher rate of gas consumption.
          also, its dangerous to be in N at an intersection… if someone rearends you… youll be in the middle of the intersection (well, if your lucky…. and dont get moved from the middle aka hit)

          • JohnP says:

            This is an interesting topic…mostly because I have gotten in the habit of shifting to neutral while at traffic lights. I began when gas prices went up and I have a difference of opinion about what some of the observations here mean. First, I agree that a car idles a little faster when in neutral but I think it’s because the engine is under the load that causes your car to roll forward as soon as you take your foot off the brake. An engine under a load can burn more fuel than an engine idling faster but not under a load. My test of this hypothesis is to shift from drive to neutral when at a full stop. The engine will initially idle up, burning gas in the system that was being allocated for the engine while stopped but in drive, and then it will idle down to its no-load idle. Now I don’t know for a fact that I am saving a significant amount of fuel and I don’t know enough about automatic transmissions to know what wear is caused by the additional shifting from drive to neutral and back to drave at a light! My other comment is that your car is technically more likely to roll out into an intersection if your car is in drive than if it is in neutral. Even if you are not hit from the rear, your car will probably begin rolling out in the intersection just as soon as you take your foot off the brake. In neutral, your engine isn’t working against the brake.

      • SoonerNATX says:

        i have a hard time believing the injectors completely shut off but will have to research since i dont know for sure.

        however, transmission wearing a myth? can you explain exactly what you mean? i question the integrity of your answers if you straight up tell me a mechanical part on a vehicle does not wear.

        • jeff says:

          When the engine computer detects that you are coasting (in gear), it shuts off the fuel supply and burns virtually no gasoline. This feature is on pretty much every car made since at least the mid nineties.
          Shifting into neutral defeats this feature and your car burns more fuel.
          Shifting into neutral at a stop is more dangerous and not advised (unless you have a car with a manual transmission). It does not increase fuel efficiency in any way to run in neutral. This is a myth.

        • Anonymous says:

          yes, some cars do turn off their injectors when your car begins to go into a coast. the wheels will continue spinning the engine and when your car gets to a low enough rpm, the injectors will come back on.

    • MoneyNing says:

      I’d think that rolling down the windows will actually waste more gas because you add so much drag due to wind resistance.

      Then again, since you are probably saving so little compared to what you use, we might be arguing about this forever 🙂

  2. Shirley says:

    The only REAL way to save on gas is to drive less.
    Consolidate your errands, carpool when practical, and walk or use a bike when possible.

    • skylog says:

      agreed. i wish the US would finally get with it with regards to mass transit as well. falling more and more behind.

      • TomSr says:

        Mass transit to drive across town? To go to the grocery store? To go to breakfast with my wife at 8:00 AM most days but sometimes 8:15 AM?

        Mass transit in cities, perhaps, but I live in a small town. Most of America is composed of small towns.

      • GoPadge says:

        We’re too big as a country for mass transit to work on an extended geographical basis. Mass transit works best with high population densities. The northeast is a good example of a functional mass transit system. But it’s not practical in most cities outside of there.

        Obviously there are exceptions, Dallas, Atlanta, LA, Chicago, etc. But even with those exceptions there are inherent flaws. Metro Dallas has three rail systems, DART covering parts of the Dallas side, TRE which connects Dallas to DFW and eastern Fort Worth and Denton County is building their own line that will allow connects between Denton and the Carrollton DART station. The biggest issue is the number of municipalities within the Metroplex that opt out of mass transit systems/stations. And with a geographical area the size of New Jersey, the area is too big to adequately service with rail service.

      • jeff says:

        Mass transit is nice (in theory), but in the real world it is highly inefficient.
        I use mass transit daily, but to get there, I have to drive. Mass transit drops you near where you have to go (sometimes), but limits what you can do when you get there. You cannot get groceries for a family of 4 using a train or bus. Besides the lack of room, you could never purchase frozen foods nor could you ensure that the fresh food you purchased stays out of the danger zone, resulting in food born illness and, possibly, death.
        Plus, mass transit runs on their schedule. I used to work nights bartending in the city. If I wanted to take public transportation home, I’d have to wait for hours or walk for miles through dangerous neighborhoods. Plus, most Americans don’t live in big cities. They live in the country, where mass transit fails the worst.
        It’s like electric cars – to city dwellers, they make perfect sense. At least until you need to go somewhere that pushes your range limits. Most of the country cannot use mass transit as efficiently as city dwellers can, and we can’t ignore most of the country…

    • jeff says:

      Not true. There are plenty of ways to save gas. My last tank on my 05 Accord LX was over 29mpg. Accelerate slowly (I never go above 2500 rpm during acceleration), mind the speed limit, limit braking, avoid lengthy idling, and properly plan your trips.

      • JohnP says:

        My last car was a 6cyl Toyota Camry with a manual transmission. I kept gas mileage records from the dealer’s lot to when I sold it at 236,000 miles. I ran 8,841 gallons of gas through it and looked at lots of different things that I thought might influence gas mileage. Things that were not significant included, grade of fuel, new air filter, a magnetic gimmick I added to the fuel line, or new tires. I agree the most important thing you can do is drive at a moderate speed. I had a trailer hitch on my car and pulling a trailer obviously also has a LOT to do with mileage. Beyond that, look at some websites that provide information about gas mileage expected for some different cars. Most trucks are really bad choices if you don’t really need a truck and 4-wheel drive likewise! Standard transmission will save you several miles per gallon and smaller engines are also better. You can save the most on gas by getting a car that suits your needs rather than getting a big, macho pickup or a soccer mom SUV just because it feels good. I saved bookoos on gas with the Camry. I got a 6cyl engine and standard transmission so I would be able to skip the truck. I periodically pulled a smallish bass boat and I moved all my belongings 240 miles on a 12ft flatbed trailer (several trips) with that car and it still has the original transmission and no significant engine work to date (almost 300K miles on it now according to present owner). Sometimes it seems that we worry about the wrong things. Gas is expensive and we need to watch our fuel budget but you just might be able to save bookoos of money by changing your ride or quitting tobacco or sodas, or buy a house rather than renting, don’t buy that new stereo system on credit, cut the cell phone habit, do your own manicure, buy food at the grocery store rather than eating out. If you do eat out, get a to-go box and allocate half of your order to the box before you take the first bite. If you don’t need to burn gas or you can find a way to use less gas do it if it makes you happy, otherwise, there may be lots of other ways to make up the difference.

  3. Strebkr says:

    I love those info-mercials. If half that crap they try to sell on TV worked everyone would be buying it. But most of it never does.

    • Chuck says:

      If it worked, all of the car manufacturers (the ones trying to squeeze 0.25mpg by a million little tricks) would install it at the factory.

    • mikestreb says:

      Remember the one about the Tornado?? Their claims were ridiculous! Something like it would save $100 a month. haha Feel bad for the idiots that fell for it and wasted their $$

  4. mannymacho says:

    I know a lot of people that subscribe to the “don’t turn off the car” myth (while waiting in the parking lot for a friend, for example), but I think just because it gives them validation to be lazy and not turn off their car.

    • govenar says:

      Separate from how much gas it takes to start the car vs. idling, what about wear & tear on the starter motor?

      • NewPerspective says:

        I’m sure it has some effect, but at the same time, my wife and I have never had a starter go out on us after a combined 54 years of driving. …and I neither of us have ever owned a vehicle newer than 5 years old!

  5. freeby50 says:

    I figured once that every minute you idle a typical car costs about $0.02 in gasoline. If you’re idling for over a minute then it makes sense to shut off the engine.

    I agree that temperature differences for gas in a given day from morning to afternoon don’t matter enough to notice. There is real science behind the cold vs warm gasoline deal but they turned it into a myth. It is true that gasoline expands when its warmer. You’d get about 10 cents more gas if you buy it in Alaska during winter compared to Florida in summer. But on a given day the temperature difference in the holding tank under ground is not going to change enough so that you’ll see a real difference.

    • SoonerNATX says:

      well if the station is following regulations then the pumps should be calibrated to the temperature. a gallon in Alaska should be a gallon in Florida.

    • mikestreb says:

      Scientifically speaking (and this ‘knowledge’ is coming from my Betty Crocker High School Chemistry class), I thought a liquid couldn’t change density without adding something to it (and you aren’t going to be adding anything to gas)? Similar to why hydraulics work, you cannot compress a liquid, right?

      Not to mention that the fuel is stored under ground where the temperature takes days or weeks to change just a single degree. I bet that the temperature of gas coming out of the pump is the same temperature all day long…

      • Strebkr says:

        Compare it to a geo-thermal system. Those are so efficient because once you hit a certain depth in the ground the tempature stay virtually the same year round. The tanks have got to be a constant temp.

    • mikestreb says:

      The vapor pressure does change considerably with temperature, but still not enough to justify what time of day you fuel up your car. I feel bad for people who waste hours of their lives stressing out about stuff like this!

  6. sophomore says:

    If you would like to research practices that really work, try googling “hypermiling.”

  7. zapeta says:

    Interesting list of myths. I save gas the easiest way, which is minimizing my driving. Most days I am able to take the bus to work or carpool.

  8. Frizz says:

    One way to save gas is to feather the throttle. Keep your gas petal off of the floor.

  9. DarkJester says:

    Uh yeah, you do need to warm up yer car in the winter. Engine oil becomes very thick & sludgey when its cold (don’t believe me? Take a partially filled container of oil & put it in yer freezer overnight. Tell me it isn’t acting like gel afterwards), so it can’t flow easily. So instead of lubricating parts as it should, there’s bare metal to metal contact going on & yer piston rings will be scratching the cylinder walls, which will lead to less power & engine failure over time. Not to mention that there will be higher pressure from the thick oil & can lead to gaskets blowing out (my sister did this to our ’90 Camry in the winter about 8 yrs ago) so yes, you should let yer engine warm up just a little (I personally let it warm up til the temp needle is just at C, which is about 85F). It might “waste gas”, but its cheaper than repairing/replacing an engine!!

  10. Rick says:

    I’m sorry, but the last line of #5 is horribly wrong. Modern cars still suffer from the real problem with cold temperatures: cold. Even with all these great miracles of technology you’re talking about, the temperature still affects a car’s initial state. Just because a car was made after the fifties doesn’t mean its engine doesn’t reach freezing temperatures if parked in bad conditions. You warm a car up to literally warm the engine and brakes to increase performance and get them to optimal temperature. They don’t stay a nice 78 degrees if you park in a snowdrift for an hour or two. Until you link empirical studies that show that stiff parts with little yield function better as moving components, I have to laugh.

  11. Zyada says:

    The reason you fill your tank when it’s cool is not because it saves money on gas.

    It’s because it reduces the amount of gasoline that evaporates into the air while your filling up, and thus reduces air pollution.


  12. Tina says:

    I tried the A/C vs the windows down trick last year. I filled up the tank with gas each week and then one week I went with the A/C on, the next I had my window down. Well, gas gauge doesn’t lie. I used more gas with the A/C than with my window down. Maybe it’s different for different vehicles? Maybe it’s different when you only have one window down vs 2 or more??? I don’t know, but I’m sticking with my window down vs A/C.

  13. 89mac says:


    warming up your car is NOT a myth and you should definitely be doing this in winter. It is VERY important for your engine to get up to operating temperature before doing anything difficult. Chances of breaking something are much higher if you are driving around on a cold engine.

    That is BAD advice.

    • jeff says:

      not completely true.
      First of all, it depends on how long your trip is. Second, it depends on the car. Third, it depends on the oil. Fourth, it depends on the ambient temperature.
      If your trip is more than 2 miles, your car needs less than 60 seconds of warmup time. Period. (unless you live if Alaska, then maybe 2 minutes). My car, even in the coldest temperatures in Chicago, takes less than a minute before it is warm enough to run without damage. The key is that you can’t start it and floor it. Drive extra lightly until your temp comes up.
      Of course, the older the car, the more likely you need a longer warmup. However, many people think warming up their car means letting it run for anywhere from 5 to 15 minutes, which is excessive no matter where you live and what car you drive. That’s where a huge amount of waste comes from. Foolish people with remote starters often will tell you that they start their car a full 5 minutes before getting in. This wastes fuel and will reduce fuel economy by quite a bit.
      I’ve had my car for 6 years and have never let it warm up for more than 60 seconds. I’ve never had a problem develop.

    • Court says:

      An engine under load warms up faster than an idling engine. The faster it arms up the faster the ECM trims the fuel mixture to stocihometric(sp?) mixture from rich. Idling nets you 0mpg. And you have to get metals very cold and push them hard to exceed the yield strengths.

      • JohnP says:

        I’m for warming up an engine for say 10 seconds minimum in the summer and longer in the winter before I go anywhere. True, modern oil and engine advances have improved lubrication but I think it’s better to wait just a bit before running up the RPM’s and shifting into gear to allow the oil to begin flowing through the engine….oil filter, to the main bearings, and up to the upper end to the cam and lifters. These parts should have an oil residue if you have a decent oil but shouldn’t the oil pump be given a chance to pressure up the system and start moving the oil before we jump out on a freeway? I also think it’s bad science to warm the engine quickly…let the metal warm up slowly rather than going from cold to operating temp in 60 seconds. I don’t have any specific data for these suggestions but I believe experience working on all sorts of engines and having additional insight from physics and chemistry classes and a good dose of common sense from the School of Hard Knocks helps me be comfortable with my opinions.

  14. Levk says:

    I think the switching to N is more or less for Stick Shift cars, not auto. If you manually change gears then its ok, if its automatic then don’t. You can harm your car that way also you may damage the shifter sooner or later with the changes so often.

    • Anonymous says:

      With modern automatic transmissions, you are correct. However, with transmissions from the 1960’s and 70’s, the transmission did not freewheel and used the engine to partially slow down the car when you let off the gas. So there was some extra gas used. Putting the tranny in neutral prevented using the engine as a brake and saved some gas.

  15. Sam K says:

    Speaking as a mechanic, #3 and #5 are just flat out wrong. Yes, the computer can compensate for a dirty air filter, but it taxes other parts of the system. It may cause the engine to run more lean or more rich, not to mention if particulates get past the filter it will put wear and tear on your Mass Air Flow Sensor, along with the delicate sensors in the throttle body.

    And to say modern engines don’t need warm up time is just dangerous advice. Unless modern engineers have somehow manipulated the laws if physics, when the engine is off oil will drain back into the pan at the bottom of the engine. Upon start up it takes anywhere from 30-60 seconds for oil pressure to get to a full operating state. Not to mention if the car has a turbo it will take several seconds for the oil to make it’s way up to the oil feed lines.

    I hate when I see stupid articles like these, follow this guy’s advice and you won’t have to wonder why your engine crapped out at 75k.

  16. Maria Barker says:

    The best way to cut gas consumption is to not drive. The second best way is to SLOW THE HECK DOWN! Plan ahead and drive 55 to 60 mph. Gentle acceleration, gentle braking, gentle turning. Get regular tune-ups. Act like your vehicle is a valuable piece of fine-tuned machinery that needs maintenance and mindful operation. It is true that vehicles do need warmed up, for 30 to 120 seconds. They do not need warmed up for several minutes. That is just sheer pollution and unwillingness to sit in a cold car while it warms. The filling the tank while it is colder is also a pollution issue (someone above pointed out), as is keeping your car running while you chat with someone. I think people have gotten confused with the reasoning behind some of these ideas and just put everything down to a wallet issue, when it is not always money that is being wasted, but more intangible things like breathable air, drinkable water, and ground not so clogged with heavy metals that it is infertile.

  17. PK says:

    Warming up the car:
    You most definitely need to warm up vehicles to protect them. However, for that you just need a minute max.
    The warm up point is addressing people that go out and turn on their car 10 to 15 minutes before they use it. The only thing they are doing here is trading money in the form of gas for time in the form of scraping ice and frost off the car.
    If you never have to scrape ice/frost, then you should just turn on your car, watch the tach for the telltale drop in RPMs that happens when the “choke” disengages and then shift and go.

  18. SpookyAction says:

    All good points except the point about letting your car “warm up”. Although it has nothing about fuel consumption, which is true, the reason why it’s recommended that you let your car warm up is lubrication. All cars have an oil pump that, as the name implies, pumps oil through your engine to lubricate moving parts. When your car is not running the oil drains out of your engine. In colder temperatures the oil has increased viscosity (it gets thicker) and takes longer to be pumped and for the heat of the engine to thin the oil out. There is some minor association between letting your car “warm up” and fuel consumption, but it has to do with the fact that the engine exerts more energy and fuel to move non-lubricated moving parts, but the fuel consumption is negligible. Letting your car “warm up” does reduce wear on your engine by allowing time for the oil pump to pump oil throughout your car’s engine, which is why it’s recommended.

  19. mike says:

    Replacing the air filter not only saves gas, but is essential for engine life. The whole purpose of the air filter is to remove contaminants (bugs, dust, leaf particles, etc.) from the air. Eventually, all this stuff clogs the filter, preventing the engine from getting enough air flow. This makes the gas burn inefficiently, decreasing gas mileage. Replacing the filter restores proper air flow, and puts the gas mileage back where it should be.

  20. RogerKopshina Sr says:

    Driving 15 miles round trip to save $.10 a gal on gas if your SUV only gets 15 mpg. Years ago my father would drive 40 miles round trip to save $.03 a gal and maybe stop for an ice cream cone on the way home.

  21. peter says:

    Article discussion about ineffectiveness that changing your air filter has in reducing fuel consumption doesn’t take into account upgrading to a k&n air filter. I found a 9% reduction in fuel consumption when I installed my k&n.

    Don’t go with cheap tires. Get longer lasting tires that have “lower rolling resistance”. Less resistance to roll equals less fuel burn.

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