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Driving for maximum mpg - worth the trouble?

I've been trying to eek out some great gas mileage from the FFH and having some success (at 45 mpg on my second tank), but it requires a lot of concentration and sometimes painfully slow driving.  I began thinking about what I was really saving per year.  The table below provides some answers, based on driving 10,000 miles per year, a gas tank size of 17.5 gallons, and gas price at $2.70/gal.


Let's say I can average 45 mpg by driving really carefully, vs 35 mpg by driving normally.  What will it cost me to drive normally?  I would use an additional 64 gallons per year, require 3 more fillups over the year, and it would cost $171.43 more.

That's a nice little savings, but contrast that with the savings I got by trading in my 1998 Audi A6 - my mileage went from 16 (call it 15) mpg to, at worst, 35 mpg.  That's 381 fewer gallons, 22 less trips to the gas station, and a savings of $1028.57 per year!

The chart on the right shows how rapidly the importance of MPG declines once you get beyond 30 mpg or so.  The chart shows gallons used per 100 miles (on the left) versus mpg (on the bottom).  You get the biggest gain when boosting mpg from 10 to 15 mpg. To get that same improvement again (3.3 gal saved per 100 miles) you need to go from 15 to 30 mpg.  Going from 30 to 50 mpg you only save an additional 1.33 gallons per 100 miles.

Maybe its not so important to eek out the very last few mpg... except when its challenging and fun.

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  • Response
    Response: George V Paris
    Very interesting ideas and concept. Thank you for the share !
  • Response
    Response: four seasons paris
    Nice way to go. Thanks for sharing !!
  • Response
    Driving for maximum mpg - worth the trouble? - Blog - Ford Fusion Hybrid
  • Response
    Driving for maximum mpg - worth the trouble? - Blog - Ford Fusion Hybrid

Reader Comments (13)

Great chart.... I traded in my V-8 pickup at 20 mpg average for my FFH. Currently, I'm averaging 35 mpg with the FFH (lots of hilly roads). The savings between 20 and 35 mpg is almost $600.00. That could be a year's worth of water bills, pay off against the Christmas budget, or eating out.

Interesting chart.... Good job.

Is it worth it? Heck yeahhhhhhhh!

June 30, 2009 | Unregistered CommenterLarry Rymal

Don't forget about the 2 other costs: The extra time it takes on the road to get you to 45MPG vs. 35MPG, and the risk of someone behind you getting fed up with the fact that you are clogging up the road and getting -er- violent (or at least wasting far more gas passing you then you saved)


June 30, 2009 | Unregistered CommenterJon

Hi again Bill,

Nice chart, and multiply those numbers X 3.5 for my driving, so it makes it a little bit more worth it, although I do not drive "granny style" when there are cars behind me (but nor do I "gun it" to appease them either). I just sold my Prius after 128,000 miles and kept tabs on every single fillup -- the result of the gas savings was $10,156.66 saved over 20 MPG, and this was using the basic moderate driving style as noted above. This was a hot topic when I first joined a Prius forum 4 years ago, that some complained about the honking and dirty looks, some people would write things like "they don't understand that I'm trying to do my part" or some other feel-good stuff. No they weren't, they were just upset because you were crawling along like a snail!!!

Each person has their own driving style and will do their own thing, but I've always practiced staying right with traffic when in traffic, then when on the road driving alone, go ahead and experiment all you want with the miserly habits.


June 30, 2009 | Unregistered Commenterjeff_h

Jeff, that's basically how I'm working it too, although I won't speed up unnecessarily to catch up to cars at a red light. I'm amazed at how much you drive per year!

Larry, I'm surprised you even got 20 mpg in that pickup!

Jon, around where I drive there's often not a lot of time difference due to red lights and stuff, but there is some and on the highway even more.

- Bill

June 30, 2009 | Registered CommenterBill Wood


Amoung other things, I teach math at the local community college. I am not surprised by this chart. Here is another way of looking at it.

Going from 10 MPG to 15 MPG is a 50% increase in gas milage. The following are also 50% increases in gas milage: from 20 MPG to 30MPG, from 30 MPG to 45 MPG, from 40 MPG to 60 MPG. In order to increase gas mileage as a percentage gets more and more challenging as vehicles get better mileage.

Anyway, I am halfway through my second tank on my FFH. I estimate I am getting 45 MPG on my little 6 mile commute to work when I do not use air conditioning. Im in the high 30's when I do use it. I will have more firm numbers when the second tank is finished.


July 1, 2009 | Unregistered CommenterKevin

Kevin, as you say, increasing your mpg by a certain percentage gets harder and harder. But even more interesting to me, the chart shows that in absolute terms you aren't achieving much above a certain point. For instance, at 35 mpg you're using less than 3 gallons per 100 miles. You can only improve 3 gallons by 3 gallons, even if you get infinite mileage. At 100 mpg you've only saved about 2 gallons per 100 miles over 35 mpg. I'm not saying I wouldn't want that, but aside from the fun/challenge, is it worth it to try and eek out 45 vs 35 mpg when you're only saving 0.64 gallons per 100 miles?

July 1, 2009 | Registered CommenterBill Wood

Bill, I believe, in economists terms, that you have just described the principal of diminishing returns. You are absolutely right that 3 gallons of gas use can only be reduced by 3 gallons. The question you pose, is 35 MPG fine, or would I rather get 45 MPG can be quite a personal one. For example, motorcycles can get great gas mileage, but is it worth it? Additionally you can strip a vehicle down, at some point sacrificing comfort with cramped interior, poor suspension, or no air conditioning. You could also sacrifice safety, or technology.

Based on myself and what I have read about other FFH owners I would say we have some or all of the following items in common:
1) We want a mid-size car, not a subcompact
2) We like technology, gadgets, etc.
3) We like AC on a hot day, even though it costs us some mileage
4) We are interested in a vehilce with a high safety rating
5) We are interested in moderate performance with regards to acceleration, handling etc.

I am not sure I have answered your question, however I will say if I have to turn off the AC to get from 35 to 45 MPG, or if I have to drive "painfully slow" as you once phrased it, then no, the increased gas mileage is not worth it for me.

July 2, 2009 | Unregistered CommenterKevin Krause


Let's see. 45 vs 35 mpg was 171.43 saved on 771.43. That is like 22. 2% interest!!! I wish a bank would give me that !!!

July 2, 2009 | Unregistered Commenterdonee

donee, LOL great point! Too bad you can't make more money that way. I might be willing to drive even slower!

Kevin, I like your FFH owner profile. I would add that we want quality and comfort.

July 3, 2009 | Registered CommenterBill Wood

Nice post. I followed the link from your post on PriusChat to see a bit more of what you were doing. There is value enough in simply looking at the question and considering the costs to each of us for the added benefit of better mileage. You noted that the biggest gain is from 10 to 15 MPG. Well . . .Take a look at the change from 5MPGs to 10MPGs, and THEN you'll see a difference that turns your head!

Seriously, there is a gain to be made whenever you improve mileage. When you ask whether it is worth the effort, then you are beginning to consider all of the other cost/benefit issues of life. Is it worth it to drive 5 mph faster? Clearly, going faster makes accidents more dangerous to all involved, so is it a good idea? Going faster than the speed limit not only is more dangerous, but it could be more costly in terms of speeding tickets. Here I've copied the post I added to the same thread you started on PriusChat:

I'm taking a more personal and practical look at it. I drive about 15,000 miles per year. If I get 35MPG, then it costs me $1,200 (at $2.80 per gallon). My 2007 Prius was getting me around 54MPG on a rolling 12-month basis, though lifetime was just above 52MPG. If I call that 50MPG, then I spent $840 per year on gas, saving myself $360 -- every year! That was enough to cover oil changes and new tires. Just think of the appeal of "free maintenance" when purchasing a new car!

I think my 2010 is going to be more of a 55MPG car (I have the Prius V, so the mileage won't be as high as the other Prius models). The move from 50MPG to 55MPG is "only" $76 per year, but it is still $76. Of course, when I compare it to 35MPG, I've saved $436 each year, and now I can start getting "free" mods on the car like window tint.

What does it cost me? I've spent some time reading PriusChat to learn about driving techniques, and I've spent a lot of time on the road learning to use them. I don't compromise safety, and I take advantage of the amenities available to me in the Prius V w/ ATP. My last trip of 840+ miles with 4 people in 90 degree heat, using cruise control and A/C on Auto, and driving on highways at posted speeds and (slightly) higher, produced a round-trip FE of 52.7MPG.

If I had been alone on that trip, I probably would have driven a bit differently, and it would have increased my gas mileage, but the real saver would have been the weight differential. I've done similar trips on my own, recently, and my FE has been as high as 58.8 for 441 miles. That still is using all of the amenities and driving at between 55 and 75mph. There is nothing wrong with saving a bit of money!

July 3, 2009 | Unregistered Commentera priori

The thing is, to get 45 (now 46) mpg in the FFH probably requires more careful driving than getting 55 mpg in a 2010 Prius. So my question about driving 35 vs 45 mpg is more for FFH drivers than Prius drivers. For 2010 Prius drivers I might have to compare 45 to 60 mpg ;-)

July 3, 2009 | Registered CommenterBill Wood

let me tell you I have looked at 100's of gowns and they have all been either too pricey or weighed way too much for a Beach Wedding.

November 24, 2011 | Unregistered Commenteraccessories

This is such a beautiful image! Is that what you call Digital Painting? It looks stunning. ltehqp ltehqp - Belstaff Winter Coats.

December 10, 2011 | Unregistered Commenterkixepa kixepa

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