Gas Mileage Myths And Facts

Ivy says:

With gas prices going sky high, everyone wants to know how to save money on gas. There’s one simple solution, of course: drive less. I’ve seen that advice on myriad message boards, blogs, LJ communities, newspaper websites, etc, etc, etc. Ah, if it were only that simple. Most of us are already driving as little as possible.

To people who live in areas where public transportation is not an option and neither is riding a bike to work, many of us are looking for that cure-all solution to get better gas mileage in your current vehicle. Many unscrupulous companies are preying on this desire by coming up with “gadgets” that are supposed to make your car get better gas mileage. Popular Mechanics has a great article debunking these gadgets. The bottom line here on these gadgets and also fuel additives is, if it seems too good to be true, it probably is.

So what are some common myths about getting better gas mileage and which are the facts? Let’s look at the myths first:

Air conditioning wastes gas. First, it depends on your definition of “wastes”. When its over 100 degrees and 100% humidity in Tennessee, any relief from that miserable heat is not a waste, in my opinion. The truth is, wind resistance at high speeds brings down your gas mileage the same as air conditioning does. A general rule of thumb here is to roll your windows down at speeds under 40 MPH and use the air conditioning at speeds over 40 MPH.

Let your car idle rather than turning it off. Unless you drive a diesel or a car with a carburetor instead of a fuel injected car, letting your car idle while you run into the store is not only wasting gas, but is also illegal in many states: check your state and local laws.

Gas is cheapest mid-week. Sure, that may have been true at some point, but with gas prices doing nothing but rising, this is now a myth. However, there may be some validity to the statement that it’s better to buy your gas in the morning. The theory is, gas expands as the temperature goes higher. I’ve not found any information to contradict that. It’s nicer to stand outside and pump your gas when it’s cooler, anyway.

So, how can you save money on gas? Here are a few tips:

If the longer way has less stop signs/lights, it may be the better way to go. Now, if it takes you WAY out of your way, no. But slightly longer routes without stop signs or stoplights is better. Keeping a consistent speed without a lot of braking and speeding up saves you quite a bit of gas.

Also important: drive the speed limit. I read somewhere that driving just 5-10 miles per hour over the speed limit can reduce your gas mileage by 15% or even more, depending on speeds and conditions. I noticed that myself on the way to and from Myrtle Beach this weekend. I drove faster on the way there and averaged about 31 MPG. On the way back, I stuck to the speed limit and averaged 34 MPG. It makes a difference!

Get rid of the extra weight. Every bit of weight adds to your fuel consumption. Is there really any need for you to be carrying the family silver around in your trunk? (I am, actually. And no, there’s no need. I just need to stop being a lazybones and get it out of my trunk.) Get everything that isn’t necessary out of your trunk. I have an uncle who, during the gas crisis in the 1970s would drive around with a quarter of a tank of gas in his car (or less) at all times. His big 1971 Land Yacht Brougham Supreme had a gigantic gas tank and he didn’t want to be hauling the extra weight around.

Aerodynamics, yo. Roof racks and all that fun stuff add quite a bit of wind resistance and makes your gas mileage suck. Don’t be a drag.

Finally, don’t drive unless you need to and combine your trips whenever possible. At least until we come up with a car that runs on garbage, our days of Sunday driving are over. I can’t tell you how much that makes me sad, but I have hope that eventually, we may be able to do so again.

What are you doing to save money on gas?


  1. AUDI DRIVER on July 23, 2008 at 11:28 am

    The drive thespeed limit tip is not allways true, it depends on the vehicle. I drive an Audi A4 1.8T and at 55mph I get 29.5 m.t.g., but at 75mph I get 31.9. This has been verified by my on board computer and my brothers aftermarket meter.

  2. Drunk Paula on May 7, 2008 at 7:49 pm

    Thanks for the advice, I need as many tips on saving gas as I can get right now with these ridiculous gas prices!

  3. Heidi @ Carolina Dreamz on April 28, 2008 at 4:44 pm

    Love these tips. I was going to link to where I read about temperatures and such.. but someone did leave that comment! 🙂 (and I’m too lazy to look for it!)

    I read that tip along with not getting gas while the tanker is filling the underground tanks.. because it stirs sediment.. it not a fuel cost savings, but it is a frugal thought to the care and maintenance of the vehicle…

    Now if we could find alternatives to shipping our food than in a diesel truck that gets less than 5 miles/gallon!

  4. Leah Ingram on April 25, 2008 at 6:28 pm

    I really like this notion of taking the slightly longer road–the road not chosen, perhaps?–as a way of avoiding traffic lights and stop signs. Brilliant.

    Also, I recently blogged about ways to get the most bang for your gas-tank buck. You can read all about it here:


  5. tink on April 24, 2008 at 10:08 pm

    Oh, per Mythbusters, leaving the tailgate down on a pick up truck does NOT save gas.

  6. tink on April 24, 2008 at 9:22 pm

    Use the cruise control.

    My gas mileage is 2 mpg better than my husbands for the same trip at the “same” speed. His speed varies a bit, mine stays consistent.

    Amazing what a difference it makes.

  7. Mrs. Micah on April 24, 2008 at 7:53 pm

    Take advantage of hills!

    It’s surprising how well small hills work when driving. Even if there’s a gentle incline, there may be no need to have your foot on the gas pedal. Experiment, particularly with your regular drives. Steeper hills work if you can maintain the momentum while going back up.

  8. Malia on April 24, 2008 at 4:33 pm

    The following is a comment DB (my husband) left at Music City Bloggers in response to a similar post over there. It’s regarding the “buying gas in the morning” concept:

    “The expansion/contraction of gasoline in an underground storage tank over any 24 hour period is negligible because the temperature change in the UST is negligible over the same time period and should not factor into the equation of when to buy gas.

    However, it is good to buy gas in the morning in summer months due to the volatility of gasoline (ie. its ability to form vapors that escape to the atmosphere). The cooler 70’s in the morning/late night help to keep vapor production to a minimum compared to pumping gas while the air temperature is in the 90’s.

    That is not so much economics as it is a public health concern.”

    (And he knows his stuff. He’s a geologist who works with companies being compliant with EPA standards and does a lot of consulting regarding underground storage tanks.)

  9. AA on April 24, 2008 at 12:49 pm

    To add to the “drive the speed limit” suggestion – don’t forget to SLOWLY accelerate and coast to a stop. 🙂

  10. FireMom on April 24, 2008 at 11:39 am

    Great post. 🙂

  11. Frugal Dad on April 23, 2008 at 11:28 pm

    Great tips for lowering the cost of gasoline by stretching each tank-full even further!

  12. La Rêveuse on April 23, 2008 at 10:50 pm

    Our hybrid also shows us the at the moment gas mileage, and we’ve found the heater uses more gas than A/C. Shocked us! We only turn it on now when we’re still cold with our mittens, hats, and scarves on.

  13. N. & J. on April 23, 2008 at 10:10 pm

    I bought a hybrid which I adore. In addition to getting better gas mileage I also have a gage which shows me when I am operating on the electric engine which makes it easier to drive so that I do. I coast as much as possible, slow down on the uphill, speed up on the downhill, I plan errands to make a loop and only run errands about once a week. Other then that I own a bike that I use to get to and from work 3-4 times a week which also helps.

  14. Ann at mommysecrets on April 23, 2008 at 9:39 pm

    Carpool with friends and neighbors. Ride together to the store, to the YMCA, to the library, or ball practice. Though with larger families, carpooling is often impossible.

  15. Ms Meghan on April 23, 2008 at 8:42 pm

    I got a new job.

    While this is hardly practical, at my old job I was a home-based therapy worker for a developmentally disabled young person. I picked them up at school & home and generally went out in the community. School was 20 min. from my house, home was 30 minutes from my house. The community was upwards of 45 minutes away from their house. I was driving ~1500 miles per month. Now I’m doing 500-700 miles per month with my job at school.

    I also try to combine errands and take the bus into the city.

  16. Carol on April 23, 2008 at 8:27 pm

    As for driving the speed limit, how does my car know that I am driving the speed limit, and it needs to use less gas?? LOL

  17. Angela on April 23, 2008 at 8:01 pm

    I try to walk when ever possible. The grocery store is only 2 miles away and if I only need a few things and it is not right when I need them, then I will walk. I also try to walk atleast once, either picking up or dropping off my son at school. We are also looking in to a electic/gas scooter, so if one of us need to go somewhere we can take that instead of the van. There is not a whole lot of highway around here, so it will work for us to have a ride that is slow, heheh