Is there anyway to tell how many MPG my truck gets?
Here is some info on it

1976 ford 300 no upgrades
1 barrel carb
3.50 rear end
4 speed tranny

What else info might you need to know to estimate the gas mileage or is it possible?

 

The easiest way to get an estimate....

Write down your mileage when you first fill your tank. Fill the tank all the way up.

Drive it for 20 miles or so, and go fill it up again.

Read how many gallons you put into the tank, from the pump.

Then subtract your previous mileage, from your current mileage. That will give you an estimate on how far you traveled between fill ups, and gives you how many gallons you burned.

Then you divide your mileage up between the gallons of gas you bought the second time, and that will give you an estimated MPG.

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I'll give you an example with example figures.

Fill the truck up and write down your mileage. Let's say it's 72500.

You do a whole day of grocery shopping, or working around town.

You go back to the station, fill it up again. Your milage now reads 72550. The pump says you put in 3 gallons of gas.

At these figures, you subtract your old milage from your current mileage to get 50 miles. Then you divide 50 miles into 3 gallons, which comes to the average of 16.6 miles to the gallon.

This will give you a close estimate.

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You also have to take into account the accuracy of your speedometer. Take the truck out on a state highway, and look for the mile markers. from the start of a mile marker read your odometer, when you get to the next mile marker read your odometer again, and subtract any difference between the two milages. If you get 0, your truck's odometer is exactly right. If you get a 1/10th or something more or less, then that is how far off your odometer is either plus or minus.

You can subtract or add the mileage to you figures to get a better estimate on gas milage.

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Here's an example. Let's say your spedometer is off minus 1/10th of a mile every mile. using the same figures as before, 72500 to 72550 and 3 gallons at the pump.

For every 10 miles traveled the odometer is off 1 mile. So in 50 miles traveled according to the odometer, in reality it's actuall 55 miles.

so 55 miles divided into 3 gallons is 18.3 MPG estimate.

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Do all the above over and over for about a month to get your average gas milage.

Let's say you tested your tuck each week of the month, and you got,

18 MPG the first week
12 MPG the second week
14 MPG the third week
16 MPG the Fourth week.

Add up the total of MPG for each week together, which equals 60. Then divide the figure 60, into the 4 weeks of testing. Your average MPG for the month would be 15 MPG.

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Hope this helps.

 

WOW, thanks man!!!

 

I would recommend just doing it one time for a whole tankful.

 

I do what 81 states but, I wait till I hit 1/2 a tank of Petrol before I fill-up.
This is how I found out on a trip to San Diego, CA from Los Angeles I managed to achieve 24mpg @55mph & 17mpg @ 65mph on the trip back.
Then over a period of time between City & Hwy driving I calculated an average 15.

 

There is a flaw with the weekly method. It assumes you drive the same number of miles each week. If most of the miles driven were at 12 mpg, the average SHOULD be low, but by just dividing by the four weeks you're giving equal weight to each week. Go with the whole tank method.

 

I usually check mine with every fill up. Not only does it let you know what your getting for mileage it lets you know how your truck is running if you drive it the same all the time.

 

Me too. I keep a log.

 

I find that when I know I am keeping track for a short time, lets say one trip, gravity does not seem to affect the right foot much, so for me to get a real estimate, I keep track of my miles and fuel fills and get an average over a long period of time. If I don't like it, I fill up and baby it for a tank then take the mileage and make myself happy

 

Why does it assume you drive the same number of miles each week? I don't see that at all.

When you average the four weeks together you are getting the average amount of MPG you got for the entire month, not your actual MPG at any given moment in time.


Let's use your number of twelve.

304 miles driven averaged to 12 mpg first week.

500 miles driven averaged to 12 mpg second week.

120 miles driven averaged 12 mpg third week.

400 miles driven averaged 12 mpg fourth week

add the four mpg together you get 48. now divide that number by four, it equals 12. You drove a total of 1324 miles and, averaged 12 MPG for the month.

In reality though the above numbers would not happen. There would be a difference, because you might be towing a trailer one week fully loaded, and not pulling anything and the truck be empty the second week etc... That will make the weekly MPG numbers higher or lower depending on what you do each week.

If you do the same weekly tests each month for the year, you can find your yearly average MPG. by adding each MPG average for each month together, and then divide that total by twelve.

You can average your mileage that you drive in a given week as well. Given the same mileage figures above, 304 1st week, 500 2nd, 120 3rd and 400 fourth. Add them all together, you get the total monthly driven miles, 1324. Divide 1324 by four and you get an average of 321 miles driven weekly.

It is still only an average however, it takes the highest number and the lowest number and averages it together to form an estimate. The example I gave also assumes you only fill up once a week. But it will still work if you fill up twice or three times a week, or only once a month. Just calculate your mileage every time you fill up, for at least four times.

averaged to 12 mpg first fillup.

15 mpg second fillup.

18 mpg third Fillup.

12 mpg fourth Fillup.

Take the four mpgs and add them together, total 58. Divide that number by four, you get your average MPG between Fillups 14 MPG.

Sometimes the MPG is lower, sometimes it's higher than the average, that'sa why it's an average.

Hope this helps.

 

When I said it assumes you drove the same number of miles each week, I was trying to say that just dividing the sum of the mpg's of each week gives equal weight to each week, where in reality each week has a different weight because some weeks have more miles.

Try this:
Week 1 100 mi 18 mpg
Week 2 300 mi 12 mpg
Week 3 200 mi 14 mpg
Week 4 100 mi 16 mpg

Multiply the miles each week times the mpg of that week....1800,3600,2800,1600.
Those total 9800. Divide that by the total miles driven all month of 700 equals 14 mpg.....which is lower than the other method because more miles were driven at the lower mpg 's.

 

Just want to say I check milage every time I fill up. I write it down in my checkbook register along w/ # of gals and find out mileage as soon as I get to a calculator. It always seems to encourage me to drive a little slower, but I also get an idea of when something isn't working.

 

I keep a little log with all the same data....it goes back to June 1983, when she was picked up at the dealer. At 170,000 miles you can imagine all the gallons of gas.