Don’t Buy a Prius to Save Money on Gas

You can now calculate different cars here:
http://dannagle.com/2012/11/miles-per-gallon-break-even-point/

You know how it goes. You are at the pump. $50 in gas later, quite annoyed, your next statement is, “I should get a hybrid.”

However, before you go buying, I would like to submit to you that a hybrid is not the way to go. Instead, you should just buy a cheaper car that uses less gas. Just like this title says, I will be using the Prius in my comparison. I have nothing particular against the Prius. I am just using it because it is the most popular hybrid. To compare, I will conveniently choose another Toyota car, the Yaris. This is to keep with a better apples-to-apples comparison. Sticking with the Toyota line helps factor in certain intangibles, like quality and general brand appeal. Both my cars will also be new.

Lets begin.

Car MSRP MPG-City MPG-Highway
Prius $24,000 51 48
Yaris $14,111 30 38

I am going to give the Prius the best chance to win. Therefore, I am going to assume your Prius never leaves the city. My test will be 51 versus 30. That is a 21 mpg difference. Lets start with the expenses. First, you have to buy the cars.

Car Item Prius Cost Yaris Cost Tally
Prius Purchase $24,000 $0 -$24,000
Yaris Purchase $0 $14,111 -$9,889

This is expected. A Prius is an “investment”. We make up the costs over time through gas savings, right? However, I submit to you that $10k is a pile of gas. Lets assume you live in a horrible gas market and paying $5/gallon. I am giving the Prius every chance to win this contest. How much gas do we break even?

\dfrac{\$9,889}{\dfrac{\$5}{\text{gallons}}} = 1,978 \text{ gallons}

Our first “break-even point” is about 2,000 gallons of gas. That means we need to put 2,000 gallons of gas in to the Yaris to balance our spreadsheet. Lets do this.

Car Item Prius Cost Yaris Cost Tally
Prius Purchase $24,000 $0 -$24,000
Yaris Purchase $0 $14,111 -$9,889
Yaris 1,978 gallons $0 $9,890 $1

We have balanced the costs. Lets start driving! How far can we drive the Yaris before we run out of all that gas? I am using Yaris city MPG because Prius does significantly better in the city.

1,978 \text{ gallons} * 30 \text{ MPG}  = 59,340 \text{ miles}

60,000 miles is a pretty good run before needing more gas. A salesman that is bad at math (or good depending on which side of the transaction you are on) might leave it at that by saying, “So after 60,000 with the Prius, or roughly a few years, it is all gas savings after that!” When he says that, you can respond, “No, sir. That covers only the initial up-front cost. I have to pay for that gas I used to drive that 60k.” The salesman will be shocked at your financial savviness and might even forgo his overpriced warranty pitch.

Anyway, so how much gas does it take to drive the Prius 60,000 miles? Once again, city driving because Prius is better at it.

\dfrac{59,340 \text{ miles}}{51 \text{ MPG}} = 1,163 \text{ gallons}

Lets add that 1,163 gallons to the Prius side of the ledger so it can catch up with the Yaris. Once again, we are using expensive $5/gal gas.

Car Item Prius Cost Yaris Cost Tally
Prius Purchase $24,000 $0 -$24,000
Yaris Purchase $0 $14,111 -$9,889
Yaris 1,978 gallons $0 $9,890 $1
Prius 1,163 gallons $5,815 $0 -$5,815

OK, the Prius has just caught up with the Yaris. We are back to apples-to-apples comparison (2 cars driven the same distance). However, we had to buy ~$5,000 worth of gas to do it. We now need to give the Yaris that same ~$5,000 to balance our sheet. I’m adding some more columns to help our miles tracking.

Car Item Prius Cost Yaris Cost Cost Tally Prius Miles Yaris Miles Miles Tally
Prius Purchase $24,000 $0 -$24,000 0 0 0
Yaris Purchase $0 $14,111 -$9,889 0 0 0
Yaris 1,978 gallons $0 $9,890 $1 0 59,340 -59,340
Prius 1,163 gallons $5,815 $0 -$5,815 59,340 0 0
Yaris 1,163 gallons $0 $5,815 $0 0 34,890 -34,890

The Prius is behind again! What happened? Well, we need to take a step back. What you are seeing is the core reason that buying a Prius to save money on gas if fundamentally flawed and where so many get the math wrong.

You are only saving money on the difference between 51 MPG versus 30 MPG. Yes, the Prius gets good gas mileage, but so does the Yaris! The cheaper the gas and the closer the MPG, the more miniscule the savings. The Prius will catch up, yes, but you have to drive a pile a miles to do it. We already up to 94,000 miles and still haven’t hit break-even! Rather than keep going back-and-forth, I am going to start deriving formulas to quickly get the ultimate answer.

Cost to drive a Prius:

\dfrac{51 \dfrac{\text{Miles}}{\text{Gal}} }{ \dfrac{\text{\$5}}{\text{Gal}}}  = 10.2  \dfrac{\text{Miles}}{\text{\$}}

Cost to drive a Yaris:

\dfrac{30 \dfrac{\text{Miles}}{\text{Gal}} }{ \dfrac{\text{\$5}}{\text{Gal}}}  = 6  \dfrac{\text{Miles}}{\text{\$}}

I calculated that for every dollar, you can drive a Prius 10.2 miles or a Yaris 6 miles. I will use those numbers along with the up-front costs to derive a formula that finds the break-even miles.


(\$24,000 - \$14,111) + \dfrac{X}{10.2 \dfrac{\text{Miles}}{\text{\$}}} = \dfrac{X}{6 \dfrac{\text{Miles}}{\text{\$}}}
X = 144,111 \text{ miles}

144,111 is the break-even mileage. Now, I will find the number of gallons of gas each car needs as well as the the costs of the gallons. This will let me complete the table.


\dfrac{144,111 \text{ Prius miles}}{10.2 \dfrac{\text{Miles}}{\text{\$}}} = \$14,128

\dfrac{144,111 \text{ Yaris miles}}{6 \dfrac{\text{Miles}}{\text{\$}}} = \$24,018

\dfrac{\$14,128}{\dfrac{\$5}{\text{Gal}}} = 4,803 \text{ gallons}

\dfrac{\$24,018}{\dfrac{\$5}{\text{Gal}}} = 2,825 \text{ gallons}

Now, lets look at our final table.

Car Item Prius Cost Yaris Cost Cost Tally Prius Miles Yaris Miles Miles Tally
Prius Purchase $24,000 $0 -$24,000 0 0 0
Yaris Purchase $0 $14,111 -$9,889 0 0 0
Prius 4,803 gallons $14,128 $0 -$24,017 144,111 0 -144,111
Yaris 2,825 gallons 0 $24,018 -$1 0 144,111 0

So there you have it. Assuming $5/gallon, and you drive your Prius only the city, you would have to drive 144,111 miles before you just break even over a Yaris!

This is an absurd number of miles just to save on gas, and gas prices could go down (note that I chose a high $5/gal). Also, I’ve made no assumptions of repairs. Your Prius will probably need a new battery before then, which can be $2,000 versus a $200 Yaris battery. Also, I made no assumptions for insurance. A Prius will cost more to insure than a Yaris. That is an increased monthly deflating gas savings the entire time it is owned. Also, no assumptions of financing. If you don’t have the full amount up-front, you are now financing an additional $10k. That could be another thousand in interest.

In short, saving money on gas is not a good reason to buy a Prius. The numbers don’t add up. If your motivation is environmental, I’d say the larger size, precious metals for complex parts, and alternate traveling options (public transit, motorcycles, or ride-shares) defeats that argument too.

If you just want to buy one because “it is cool”, I will not argue with that. It is a cool and fun car. Go ahead and buy it for that reason. Whatever the reason, know why you are buying it. Just don’t kid yourself that the reason is an “investment” to “save money” or “save the environment”.

Posted in Editorials
23 comments on “Don’t Buy a Prius to Save Money on Gas
  1. What on earth says:

    This is the most difficult to understand tabling system I have ever seen. It’s almost too hard to follow.

    • dan says:

      It is a combination of ledger and double-entry bookkeeping system. I am tracking multiple columns to try to keep a zero balance. That’s how I know both are equal.

      It was the best method I could think of to track all the columns at once, such as gas and miles. Perhaps it’d be better if I just hid the tables or reorganized it to a more standard approach since it got pretty crazy when I started tracking the miles too.

  2. mansharra says:

    The author completely neglected feature parity, which is a common mistake people make when comparing the Prius to econocars. The version of the Yaris he made the comparison to has a manual transmission, and is missing things like cruise control, power windows, and keyless entry. The base level Prius already has all this. Factor in feature parity (5 door LE with automatic transmission), and the Yaris’ price rises to $17,225.
    Secondly, for the size of car being compared to, the proper hybrid to compare to is the Prius C, not the Prius. That car starts at $19,000 (with cruise control, $20,695).
    At these prices, and accounting for feature parity, the Yaris costs $1,800 per year in fuel, while the Prius C costs $1,150 (assuming EPA-standard constants of 15,000 miles per year, 45% highway, 55% city). This translates into an annual fuel savings of $650, leading to a breakeven time of 5.3 years, or 79,500 miles at current fuel prices. Kick it up to $5 per gallon prices per the author’s assumption, and the breakeven time falls to 4.1 years, or 61,250 miles. That means the actual breakeven time, per the author’s assumptions, is actually less than half that of what they came up with (144,000 miles)!
    Finally, the market segmentation of people shopping a Prius has minimal overlap with those who buy Yarises. Prius owners are generally people looking to scale down from higher end cars without sacrificing amenities they are used to, while Yaris owners are best described as the most value-conscious of car buyers. The comparison between a Yaris and a Prius would rarely ever come up in the first place.

  3. Chris says:

    In terms of interior space and cargo capacity the Prius and Yaris are in completely different classes; very much apples and oranges. How about picking a vehicle that’s actually comparable to the Prius?

  4. redditor says:

    I’ll just post this comment I read about this article on Reddit
    “There are so many things wrong with the author’s comparison, I don’t even know where to begin…

    The author completely neglected feature parity, which is a common mistake people make when comparing the Prius to econocars. The version of the Yaris he made the comparison to has a manual transmission, and is missing things like cruise control, power windows, and keyless entry. The base level Prius already has all this. Factor in feature parity (5 door LE with automatic transmission), and the Yaris’ price rises to $17,225.

    Secondly, for the size of car being compared to, the proper hybrid to compare to is the Prius C, not the Prius. That car starts at $19,000 (with cruise control, $20,695).

    At these prices, and accounting for feature parity, the Yaris costs $1,800 per year in fuel, while the Prius C costs $1,150 (assuming EPA-standard constants of 15,000 miles per year, 45% highway, 55% city). This translates into an annual fuel savings of $650, leading to a breakeven time of 5.3 years, or 79,500 miles at current fuel prices. Kick it up to $5 per gallon prices per the author’s assumption, and the breakeven time falls to 4.1 years, or 61,250 miles. That means the actual breakeven time, per the author’s assumptions, is actually less than half that of what they came up with (144,000 miles)!

    Finally, the market segmentation of people shopping a Prius has minimal overlap with those who buy Yarises. Prius owners are generally people looking to scale down from higher end cars without sacrificing amenities they are used to, while Yaris owners are best described as the most value-conscious of car buyers. The comparison between a Yaris and a Prius would rarely ever come up in the first place.”

  5. Kyle says:

    Now compare the Yaris to the Prius c, a smaller, cheaper more comparable vehicle to the Yaris. It also gets 2 more city MPG. I’m too lazy to do the math but I am guessing a break even point of somewhere around 60-80k miles.

    Regarding environmental impact, larger size has no impact on the environment unless you mean the additional materials used to construct it. Precious metals are recyclable. Americans love vehicles and many need to have one regardless so alternative transportation is rarely a viable option over owning a car.

  6. Levi says:

    I just came home from the Toyota dealership in Erie, PA. The proper comparison should be the Prius to the Camry. In the areas of Interior space and features, they are very very similar. I was looking at the high end Prius $33,500 and the Camry hybrid $35,000. The Camry ride is leaps and bound above the Prius, and the interior of the Camry is a little more spacious. However I am 6’3″ and I could fit in all seats in both the Camry and Prius. The Prius gets 50 mpg average, the Camry hybrid gets 40. I chose the Camry because I felt the difference in price wasn’t enough to justify the sacrificing of driving quality that you do when you drive the Prius. It’s still amazing fuel economy and its a great car. But the author of this article should have compared the base Prius $21,000 to the base Camry $22,000.

    • Maneesh says:

      I totally agree with you. The ride quality in the Prius is compromised due to several factors, but it gives great gas mileage. However, if you think about it, in the long run there are really no savings by driving a Prius, because you are more likely to use all the saved money on a good physiotherapist to bring your body back into proper alignment. No jokes. The Prius is not ergonomically designed for comfort driving, and after driving it for several hundred thousand miles, your body and lower back start breaking before their time. Also, people somehow spend more money out of their pocket on other items thinking they are saving money on gas. They actually spend more on other things. So in my humble opinion, Camry is the winner.

  7. way And says:

    And what about factoring in things like:1) Brakes changes, (my Prius has 98,000 mi and not one brake pad change) 2) Oil changes -every 5000 mi,. 3) NO California Smog checks fees$- which will eventually equal more cost if your car does not pass–which is just a matter of time. 4) Also if you buy one of the first 60,000 Prius’ sold you get a $3700 gov tax off and Rebate from California state $1500.

  8. Jon says:

    Also the Pbattery will not need to be changed until much later, as the hybrid battery will most likely outlast the car itself. The author seems to have confused the expensive hybrid battery with the cheaper 12 volt battery which does need to be replaced and costs less than $200. My prius has over 120,000 miles and shows no signs of needing the hybrid battery replaced.

  9. inky says:

    Exactly! You need to be comparing vehicles with the same features, size, cargo room. I can’t fit my three dogs into a yaris and go away for a weekend. I WISH I could but that isn’t happening. The prius is closest to a station wagon I can get.

  10. sciredrocks says:

    Wanna save the earth? Drive a moped you snobs…

  11. Anna says:

    Love the analysis! Could you do a comparison with a car that has the same amount of interior space, (driver legroom, shoulder room, cargo space)? I need a car that can fit me, the spouse, and 2 teen-agers, with heights ranging from 5’7 to 6’2. We fit in a Prius, we don’t fit in a Yaris. We do fit in a Matrix. We have a Vibe (the American twin of the Matrix). We’re looking to get a car that has the same interior space but much better gas mileage, and we think a gently used Prius might be the answer.

  12. The title of the article is “Don’t Buy a Prius to Save Money on Gas.” That is a single aspect of the overall cost of vehicle ownership. That it is highlighted in the title means that this article should focus on only a single topic. But it does not; to start with the purchase price (though a reality) is not the advertised purpose of the article based on the title.

    It has been my 9 years of Prius ownership that people choose the Prius rather than an Accord, Camry, BMW or Lexus. Most people are not torn between a Prius with standard amenities and a stick-shift Yaris with hand-crank windows. In many cases, the vehicles being compared truly are apples-to-apples in terms of purchase price.

    But all the same, let’s run the numbers. This time, we should keep them simple.
    Drive each car for 12,000 miles purchasing $5.00 gasoline.
    Prius = 235 gallons of gas @ $1,176
    Yaris = 400 gallons of gas @ $ 2,000

    There’s really not more to say since I’ve already saved $823 in gas by driving my Prius. And wasn’t that the point of the article’s title? I have 113,000 miles on my 2004 Prius; if gas cost $5.00 the whole time, I would be ahead almost $35,000 by now.

    Additionally, if I may, this article uses the purchase price of the Prius Liftback ($24,000). Anyone with the Yaris in mind would most likely consider the Prius c with a base price of $19,080 and 53 mpg. Cheaper and more efficient than the Liftback.

  13. Asim Malik says:

    hey Dan,

    I enjoyed reading this — but I think it is fundamentally flawed in one major way. Supposedly the gas engine does not kick in at all on the Prius until you hit above 40MPH. I think that is for older versions, who knows if its higher in newer versions.

    There are some other factors too. If the A/C in the Prius is on for too long, remember that it runs off the same battery pack as the electric portion of the car. So technically even if you are below the 40MPH, the gas engine would kick in if the battery was drained from A/C use.

    All in all I think your article is fair; but just keep in mind what I said about *when* the gas engine kicks in should be relevant to your analysis.

  14. dj says:

    i bought my prius for 8,000, now you do the math

  15. steve says:

    Nobody talks about safety……I would prefer to buy a large safety car and pay for my safety. Those gas efficient cars are jokes when the hit SUV or a truck. Think about it please.

  16. greg says:

    I didnt purchase a prius to save money I purchased a prius to save the environment.

  17. Your comparison is irrelevant and makes no sense. Trying to tell people they are not saving money and were overcharged. Compare the Prius with a car that costs the same. How can you compare a Prius with a Yaris? Compare the Prius with a Camry and then tell me I’m not saving. Thanks for tour waste of time.

3 Pings/Trackbacks for "Don’t Buy a Prius to Save Money on Gas"
  1. [...] let’s look at the cost efficiency of it – and I mean more than gas. A came across a blog on DanNagle.com that made some great points. He compared buying a new Prius, to buying a Toyota [...]

  2. […] One of the many problems with adopting, implementing, and testing Common Core is the included rush to invest in technology. That technology rush is also being highlighted with the rise in calls for computer-graded writing. [The perceived efficiency of such investments in technology are myopic, I argue, much as purchasing a Prius for the narrow gas savings that many consumers fail to place in the larger purchasing investmentĀ (see also).] […]

  3. […] One of the many problems with adopting, implementing, and testing Common Core is the included rush to invest in technology. That technology rush is also being highlighted with the rise in calls for computer-graded writing. [The perceived efficiency of such investments in technology are myopic, I argue, much as purchasing a Prius for the narrow gas savings that many consumers fail to place in the larger purchasing investment (see also).] […]

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