Science project

Fuel Efficiency

Research Questions:

  • What is the most fuel-efficient combination?
  • What is the most cost-effective combination?
  • Is higher octane rated gasoline worth it?

The rising cost of oil in recent years is prevalent at the pump. Costs have waivered between $1.60 and $4.00 within the last 3 years. Driving is inevitable, especially in areas without public transit systems, so it is important to not only maximize fuel cost but also fuel efficiency to reduce the strain on the environment. For this project students will collect fuel cost and consumption data, comparing different fuel combinations, then compare which is the most fuel efficient and cost effective.


  • Octane-rated unleaded gasoline 
  • Fuel additives
  • Automobile with a functional odometer.

Experimental Procedure:

1)     Determine your grade of fuel. The procedure will differ between engines. Most cars use 87-grade gasoline while others require 91 grade. Consult your owner's manual for information regarding fuel grades.  

2)     Choose three fuel combinations to test.

a)     If your car only takes a certain grade you should only test that grade. Consult your owner's manual regarding fuel additives.

b)     If you car has a minimum octane grade be sure to test that grade and higher.

c)     Testing Variables: Example

i)       87 Grade Only

ii)      91 Grade Only

iii)     87 Grade with fuel additive

3)     Gas up. Record the grade, cost per gallon, number of gallons added, and total cost. If using a fuel additive record the volume added and cost of the additive. You should also record the volume of the gas tank, which is available in your owner's manual.

4)     Record your odometer reading. If you have a trip odometer reset it to zero.

5)      Drive as usual. Since you will be assessing fuel-efficiency and cost for daily use do not try to decrease or increase usage. (i.e. Road trips, unusually slow or fast driving scenarios).

6)      The next time you require a fill up record the odometer reading. When you fill up with gas record the volume added.

a)     How can you calculate the volume of fuel consumed based on this data?

7)     Organize and compare your data in a chart.

8)     Calculations:

a)     You know the following:

i)       Volume of gas tank

ii)      Cost per gallon

iii)     Number of gallons added

iv)    Total cost of gas

v)     Odometer readings (between fuelling).

vi)    Cost of fuel additives

vii)   Volume of fuel additives

b)     Calculate total volume of gas consumed.

c)     Calculate miles per gallon (mpg).

d)     Calculate cost per mile

For fuel additives factor in the cost and volume.

Terms/Concepts: The basics of automobile engines; Octane Rating; How to calculate miles per gallon (mpg) and cost;  Fuel Additives



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