When are You a Doofus for Driving Out of the Way for Cheap Gas?

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I sat paralyzed (not literally) at the intersection.

Just a few moments before, I pulled up my Gas Buddy app ( a free App I highly recommend) and found out what I always found out – that Sam’s Club had the cheapest gas in town.  The Sam’s was 1.5 miles in the wrong direction.  The gas gauge was on empty.

The closest gas station that I’d be passing had gas for $3.25 per gallon, but it was $3.20 at Sam’s.

What should I do? Is it worth driving out of the way for cheap gas?

In the end, I decided to do what any logical person would do: don’t get any gas, and be sure to rush home and write a post about how to calculate how far out of your way you should drive to get cheap gas.

My trial becomes your convenience.

Is it Worth Driving Out of the Way for Cheap Gas?

You’ll need a few bits of information before you possibly begin to logically answer this question.

1.   How many miles per gallon do you get in your vehicle?  When we were in PNG, we kept a gas log so we could know our miles per gallon.  It’s a simple thing to do.  Write the odometer reading when you get gas, and the next time you get gas write your odometer reading and the number of gallons you added.  The difference in the odometer reader is the distance you’ve traveled on the number of gallons you added.  Let’s say you’ve travelled 150 miles, and you put 5 gallons in your tank.  Take 150/5, and you’ll find out that you’re getting 30 miles per gallon.  Personally, I wish that was the case for our illustrious PT Cruiser.  This gas sucking car gets us about 17.5 miles per gallon in town.

Remember: Be sure you know how many miles per gallon you get around town as your town driving will probably be more reflective of your driving to a gas station.

Tip: As an alternative to keeping a paper record, if you have a smart phone you could get an App like Gas Cubby (free).

2.  Where is the cheapest price of gas and how far away is it?  What is the price of gas at the closest gas station?

If you don’t have a Gas Buddy App on your phone, you can always visit gasbuddy.com on your home computer.  When you do this, you’ll be able to find out how far away it is for the cheapest gas, and you’ll know how much it is at the closest location.

3.  How much gas do you need?  Do you know your fuel tank size?  When it’s on empty, how many gallons or liters does it take to fill?  How full or empty (depending on your life outlook) is your gas tank?

The Math Formula: Is it Worth Driving Out of the Way?

Distance you need to drive: In my example above, 3 miles out of the way.

Cost to drive that distance: At 17.5 miles per gallon and $3.25 per gallon (what I paid the time before), I’d pay .1857 per mile.  (price per gallon / miles per gallon; in my case 3.25/17.5).  Now that I know how much it takes in gas to drive a mile, I multiply that by the number of extra miles I’d need to drive to get to the cheaper gas station.  Thus it would cost me 56 cents (.1857*3) to drive 3 miles out o the way for the closest gas station.

Distance to gas station * cost per mile = how much it costs to get to the gas station

My tank is a 13 gallon tank, and my gas light just came on, so I probably needed about 11 gallons (the light comes on when I have two gallons left).  Since Sam’s was .05 cents per gallon cheaper, I’d save .55 cents there.

Savings per gallon * total number of gallons needed = total amount you could save

End result?

It would not be worth driving 3 miles total to save 5 cents per gallon because it would cost me more in gas than I would save.  Even if I could save more by driving to the gas station, I still haven’t factored in the time involved and other costs like oil cost and wear and tear on the vehicle.

Is this a waste of time?

Possibly, but likely not.

I’ve done this once, so I know how much I can use as a general rule for cost per mile.  From now on, I can do the math easily in my head.

It’s taken me about 20 minutes to come up with this post and work out this little math formula.  If I could save $1 every time I get gas because I make savvy spending decisions, then I could save at least $50 this year.  That’s like getting $150 an hour.  It’s worth it in my book.

The best part is this helps me decide when I should run to a second grocery store because they have a sale.  Does the cost in gas justify the extra savings?  This helps when considering making an extra trip to do something.  Does the cost in gas justify doing this today, or should I just do it next time I’m out and about?

Remember, if you drive a lot or have a massive vehicle that holds dozens of gallons, you’re savings can add up even more quickly.

Do you ever drive out of the way to get gas?  Have you ever figured out your cost per mile?  Do you think this whole exercise was a complete waste of your time?



  1. says

    Gas is an interesting focus if only for the obvious irony of wasting time and money (the burning gas) to go find the cheap gas.
    The concept can be expanded to any trip made to buy anything on sale. For example, I love Costco, but my nearest one is over 15 miles away. So it’s about a 40 minute round trip, and nearly $6 in gas. I rarely go to Costco from the house. When I know I’ll be near it, I go on the way home.

    Similarly, when I ask the mrs what she’s up to on an errand day, she’ll mention two stops, but remark that she’s coming home in between. Picture a 3 sided triangle. Ten miles between corners. I’ve explained to her that a round trip to each of the two stops is 40 miles, but go from one to the other, and it’s now 30.

    I’m guilty of over-thinking some of these things, but in the end, I’m happier reducing both my gas burned and the time spent driving at the expense of just a bit of planning.

    • says

      Living in Cheyenne, I’ve realized that we really need to plan our trips well. This city is so spread out. I think that makes a huge difference in our total monthly gas bill. We get gas at Sam’s when we are there (or next door at Walmart) otherwise we get it where we are (with the help of Gas Buddy).

  2. Art Ford says

    Another interesting exercise (at least it was to me) involved calculating how much less I would spend on gas if I upgraded from my current car to one that is more energy efficient. While it would be nice to have an excuse to upgrade, I decided the costs didn’t make sense for me when savings were compared to the cost of the upgrade. I found I wouldn’t save as much as the pundits seem to indicate.

    • says

      I was thinking it might make sense for me to grab a calculator and see what kind of a difference it would make on a year of gas. I’m guessing it wouldn’t be enough to justify the cost of a new card, but I haven’t done any calculations yet …

  3. says

    I always laughed at my friend that would drive 15 miles in DC traffic to go to the Sam’s club by his parents house to get gas… he had no clue he was wasting money and when you’d try to explain it he wouldn’t listen… oh well. Maybe I should show him this post :)

    • old pal says

      I can’t say it’s why I own a motorcycle… but it only makes cents to deal in pennies difference rather than dollars. (I realize the two wheeled argument isn’t for the faint of heart or the parent toting kids… for that argument I use my toyota echo).

      • says

        Hey ‘old pal’,

        Nice to hear from you. So can you hook up car seats to a motorcycle? Do you have any good talking points for convincing the mrs of the value of a motorcycle? Any idea how to stay warm on a motorcycle when it’s snowing and the wind is blowing a hundred miles an hour?

        Alright, I might need to look into an Echo…

        If so I’m game!

    • says

      That doesn’t make any sense does it? Hopefully he’ll eventually realize that his ‘cheap gas’ is costing him more money and waisting his time.

  4. says

    I always make it a point to fill up when I am near the cheapest gas stations. That way I don’t waste gas to save a few pennies. I also have a gas credit card that really helps to make gas even cheaper.

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