Apr 21 2008

I like to calculate my car’s mpg


How many miles per gallon does your car get? You might know what the manual says it should get, but do you know for sure?

My car’s manual states that my car should get 23 mpg in the city and 31 on the highway. My actual gas mileage is better than that, and I like to calculate it to see how my car is doing.

I usually fill up my gas tank all the way, then I reset the trip odometer to zero.

I drive for a week or two or three until I’m down to about 1/4 tank or so. I fill up again and pay attention to the exact amount of fuel I’ve just added. I grab my cell phone, click to the calculator function, and divide the miles on my trip odometer by the amount of gas I’ve just put in.

For example, say I drove 350 miles according to my trip odometer, and filled my tank all the way and added 10.6 gallons. 350 divided by 10.6, and I’d see that I got 33 miles per gallon.

My method only works if I previously filled my whole tank, and then filled it up again on the subsequent fill-up.

Do you calculate your miles per gallon like that?

If my gas mileage is a bit lower than normal, it’s a cue for me to check my tire pressure, watch my driving habits (how fast I accelerate and brake), and clean out my trunk and back seat to remove extra weight.

During our weekend trip to Indiana, we got about 33 mpg. I’ve gotten 40 mpg in that car before (during a trip that was solely in Indiana–no hills and crazy turns like in PA).

Because I know my miles per gallon on that trip, I know that it’ll take 25 to 27 gallons round-trip. At $3.35/gallon (what I paid when we left), that’s $83.75 if I get 33 mpg, and $90.45 if I get 31 mpg. At $3.49/gallon (what I paid when I got home), that’s $87.25 at 33 mpg, and $94.23 at 31 mpg. Sigh. I guess that’s still cheaper than a plane ticket!

Today, though, I’m going to get zero mpg. I’m going to walk to do my errands, since it’s such a beautiful day and we just put about 900 miles on the car.

Posted under Uncategorized | 11 Comments »

11 Responses to “I like to calculate my car’s mpg”

  1. My car calculates it for me. It’s kind of like a game for us–we’ve even got our kids watching it and get cheers when we hit a new high number!

    TheCFONow’s last blog post..They’re Talking About Me!

  2. When I drive from Chicago TO Indiana to get gas I set the the odometer back to 0 (not the official one but the one you can change) and then start counting for the next week or so.

    How’d the contest we all work out? Anybody win?

    Dave from Welcome Back Rosenthal’s last blog post..I Need to Go Somewhere. I Should Look for a Cheap Travel Deal

  3. Hey Dave–

    My husband and I are working on the contest results–we have to confirm that winning entries are valid and stuff. We hope to post the results soon! If not today, then tomorrow. Thanks for checking!

  4. I haven’t tried that before but should start the hubby works about 1.5 hours from the house so we usually just budget really high for gas and make up for it in other places.
    Maybe this will help bring it down a touch.

    Dirkey’s last blog post..Joy in the small things-An Earth Day Contest

  5. Ever since I started driving, I’ve done this. on our weekend trip to & from Wisconsin, we got 39 MPG in our little Civic! It is a game, really :)

    joanna’s last blog post..Uncle Chris

  6. We in INDIA calculate average KM per Ltr. Usally car goes 15 KM in one liter Petrol that amounts to us$1

    Shanker Bakshi’s last blog post..Miscellaneous Ramblings of a dot com Guru April 21 2008

  7. I do love calculating it. :) I get about 30 plus because I drive almost always on the freeway. Considering it’s a Rav4 I think that’s darn good.

    castocreations’s last blog post..Birthday Celebration Sponsor – InVita Paper Studios

  8. I do mine the same way. My 99 escort gets a bit over 30mpg; the 91 civic I had till it’s recent retirement got an average of 35 (28-45mpg, depending on weather/driving habits). I like seeing how good I can get the mileage.

  9. We like to calculate mileage too! Its an important factor in the overall health of your engine … If you’re mileage drops off unexpectedly it could be a sign of something wrong in the engine or fuel systems. Keeping track of mileage is nice if there are other “symptoms” of trouble in your car .. a mechanic can use it as a clue in diagnosing any problems .. and catching problems when small and inexpensive to fix is a lot more frugal than waiting until something catastrophic happens!

  10. I do this every time I fill up too! It’s been very depressing lately… I used to only drive on the highway, but since I started working, I only drive on the streets. My one way commute is 10 miles with 20 (I counted!) traffic lights – it’s horrible.

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Hey! I'm Kacie, wife and mother of 3. I write about my family's finance: how we save money, improve our spending, and plan for the future.

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