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When you have a car, you may want to know the fuel consumption efficiency of your car. It is very easy to calculate the average miles per gallon by just gathering some information.

Things You Will Need

• Pen or pencil
  
• Fuel (gasoline or diesel) receipts
  
• Blank Record of Fuel Purchases form (similar to the one below)

Car: Toyota   Model: Corolla   Year: 2005

Date	Odometer Reading	Total Miles Driven	Total Gallons (Qty)	Unit Cost Per Gallon	Total Gallons Paid	Average Miles Per Gallon
5/01/12	32,568		3.86	$3.89	$15.00
5/08/12	32,920	352	3.89	$3.89	$15.00	23.47
5/14/12	33,245	325	3.93	$3.82	$15.00	21.67
5/22/12	33,587	342	4.22	$3.79	$16.00	21.38
5/30/12	33,908	321	3.96	$3.79	$15.00	21.40
6/05/12	34,250	342	4.53	$3.75	$17.00	20.12
6/11/12	34,579	329	4.02	$3.73	$15.00	21.93
6/16/12	34,903	324	4.08	$3.68	$15.00	21.60
6/26/12	35,298	395	4.93	$3.65	$18.00	21.94
7/03/12	35,622	324	4.18	$3.59	$15.00	21.60

To calculate the Average Miles Per Gallon:

1.  Deduct PREVIOUS Odometer Reading (last refill) from the CURRENT Odometer Reading =  Total Miles Driven

2.  Total Miles Driven divided by Total Gallons Paid = Average Miles Per Gallon

STEPS

Step #1 – Prepare a blank Record of Fuel Purchases (RFP) showing the date, odometer reading, total miles driven, total gallons (quantity), unit cost per gallon, total gallons paid, and average miles per gallon.  Write the name of the car, model and year.

Step #2 – Buy gasoline from a gas station and ask for the receipt. Get a pen or pencil and write the odometer reading on the gasoline receipt.

Step #3 – Based on the gasoline receipt, write the date, odometer reading, unit cost of gasoline, quantity of gasoline purchased and the total amount paid for the gasoline on the RFP.

Step #4 - After a week or so when you go to a gas station to refuel, repeat Step #2 and Step #3. On the second gasoline purchase, you can divide the Total Miles Driven by the Total Amount paid for the gasoline to arrive at the average Miles per Gallon. Write the number on the RFP.

Step #5 – Repeat Steps #2, #3 and #4 until you complete the whole one month, 2 months or 3 months.

You can repeat the above steps after 6 months to determine if there is something wrong with your car fuel consumption efficiency.

What will the average miles per gallon information tell you?

• If your average miles per gallon are very close to each other or almost the same, then your driving habits are very good.
  

• If your average miles per gallon fluctuates more than 20% of the average miles per gallon, then you might be overspeeding, there is a gasoline leak, the aircon is being used even it is not necessary, doing a lot of stop and go driving, or the tires are not properly inflated.