24th Grade Science Fair
Experiment 1
Observation
Vehicle fuel efficiency is usually listed in two parts: highway average mileage and city average mileage. Two numbers are listed because each driving style involves very different acceleration and braking profiles. Highway miles are usually driven at a reasonably constant speed with only occasional need for acceleration and braking. City driving typically involves "stop and go" driving in which a vehicle decelerates to a complete stop before once again accelerating to the desired speed. The frequent braking in conventional vehicles causes the vehicle's kinetic energy to be dissipated as heat and noise during the braking process, resulting in lower average efficiency. Acceleration is also more energy-intensive than simply maintaining velocity.
Hypothesis
Shorter spans of time between fillups should correspond to faster average driving speed. Faster average driving speed should correspond to higher proportion of time spent driving "highway miles". Higher proportions of time driving "highway miles" should correspond to higher average mileage over the life of a tank of gasoline. Therefore, shorter times between fillups should correspond to higher average mileage over the life of a tank of gasoline.
Materials
Over the span of 32 months, data was recorded at the time of gas fillup. This data consisted of the date, the amount of gasoline added to the tank, and the number of miles driven since the previous fillup. No special effort was made to control for driving style. No special effort was made to control for terrain, road type, weather, vehicle maintenance condition, or traffic conditions. No special effort was made to control for geographic area, and while the vehicle spent most of its time in the Cleveland Ohio area, it also was driven in Michigan, Indiana, West Virginia, Pennsylvania, New York, and Ontario. Driving speed varied based on location, based loosely on the posted speed limit. The gasoline tank was filled 79 times during the course of the experiment. The first data point was discarded because the date was not recorded. The second data point was also discarded because there was no information about time since previous fillup.
Results
A scatter plot was used to show the average mileage for each tank of gasoline and period of time over which that tank of gasoline was used.
Some outlier points are known to be the result of recordkeeping errors. Some outlier points are known to be the result of most of a tank being driven in one session, followed by a period on non-use of the vehicle.
The data points that are clustered near the Y-axis (X values from 0 to 2) are most likely the result of extended periods of highway driving with rapid refilling necessary. The data points with higher values on the X-axis are likely to be the result of mixed driving, as characterized by short trips interspersed with periods of non-use of the vehicle.
Conclusion
The data supports the hypothesis. Shorter times between fillups appear to correspond with higher fuel economy.
Based on visual estimation, it appears that the vehicle averages approximately 26mpg on the highway (durations between 0-2 days), and approximately 20mpg in mixed driving (durations of 2+ days). The EPA estimates (2008 method) of highway and city mileage for this vehicle type are 26mpg and 17mpg (citation). The author suspects that the trend around 20mpg can be explained by the geography of the Cleveland Ohio area, which encourages mixed highway and city driving, thereby raising the figure above 17mpg.
Experiment 2
Observation
The Clean Air Act requires various different blends of gasoline to be sold at different times of the year, based on pollution profiles as each blend is burned in automobile engines. "Summer gasoline" blends require the removal of some volatile organic compounds which can contribute to smog production when burned (citation). Winter blends do not have the same refining requirements. Gasoline blends with different refining requirements should have different energy content and fuel efficiency profiles. Conventional wisdom asserts that summer blend gasoline yields higher fuel efficiency.
Hypothesis
Summer blend gasoline should produce higher fuel efficiency readings during the time period in which it is sold.
Materials
Over the span of 32 months, data was recorded at the time of gas fillup. This data consisted of the date, the amount of gasoline added to the tank, and the number of miles driven since the previous fillup. No special effort was made to control for driving style. No special effort was made to control for terrain, road type, weather, vehicle maintenance condition, or traffic conditions. No special effort was made to control for geographic area, and while the vehicle spent most of its time in the Cleveland Ohio area, it also was driven in Michigan, Indiana, West Virginia, Pennsylvania, New York, and Ontario. Driving speed varied based on location, based loosely on the posted speed limit. The gasoline tank was filled 79 times during the course of the experiment. The first data point was discarded because the date was not recorded.
Results
A scatter plot was used to show the average mileage for each tank of gasoline and the numerical day of year on which that tank was purchased.
There is no discernible trend based on date.
Conclusion
The data is unable to support the hypothesis. There are too many uncontrolled variables that affect vehicle mileage other than gasoline blend.
Observation
Vehicle fuel efficiency is usually listed in two parts: highway average mileage and city average mileage. Two numbers are listed because each driving style involves very different acceleration and braking profiles. Highway miles are usually driven at a reasonably constant speed with only occasional need for acceleration and braking. City driving typically involves "stop and go" driving in which a vehicle decelerates to a complete stop before once again accelerating to the desired speed. The frequent braking in conventional vehicles causes the vehicle's kinetic energy to be dissipated as heat and noise during the braking process, resulting in lower average efficiency. Acceleration is also more energy-intensive than simply maintaining velocity.
Hypothesis
Shorter spans of time between fillups should correspond to faster average driving speed. Faster average driving speed should correspond to higher proportion of time spent driving "highway miles". Higher proportions of time driving "highway miles" should correspond to higher average mileage over the life of a tank of gasoline. Therefore, shorter times between fillups should correspond to higher average mileage over the life of a tank of gasoline.
Materials
- One Oldsmobile Intrigue GL (2000 year model with 3.5L V6 engine)
- 1100 gallons of 87 octane gasoline
- notepad
- pen
- snacks for driver
Over the span of 32 months, data was recorded at the time of gas fillup. This data consisted of the date, the amount of gasoline added to the tank, and the number of miles driven since the previous fillup. No special effort was made to control for driving style. No special effort was made to control for terrain, road type, weather, vehicle maintenance condition, or traffic conditions. No special effort was made to control for geographic area, and while the vehicle spent most of its time in the Cleveland Ohio area, it also was driven in Michigan, Indiana, West Virginia, Pennsylvania, New York, and Ontario. Driving speed varied based on location, based loosely on the posted speed limit. The gasoline tank was filled 79 times during the course of the experiment. The first data point was discarded because the date was not recorded. The second data point was also discarded because there was no information about time since previous fillup.
Results
A scatter plot was used to show the average mileage for each tank of gasoline and period of time over which that tank of gasoline was used.
Some outlier points are known to be the result of recordkeeping errors. Some outlier points are known to be the result of most of a tank being driven in one session, followed by a period on non-use of the vehicle.
The data points that are clustered near the Y-axis (X values from 0 to 2) are most likely the result of extended periods of highway driving with rapid refilling necessary. The data points with higher values on the X-axis are likely to be the result of mixed driving, as characterized by short trips interspersed with periods of non-use of the vehicle.
Conclusion
The data supports the hypothesis. Shorter times between fillups appear to correspond with higher fuel economy.
Based on visual estimation, it appears that the vehicle averages approximately 26mpg on the highway (durations between 0-2 days), and approximately 20mpg in mixed driving (durations of 2+ days). The EPA estimates (2008 method) of highway and city mileage for this vehicle type are 26mpg and 17mpg (citation). The author suspects that the trend around 20mpg can be explained by the geography of the Cleveland Ohio area, which encourages mixed highway and city driving, thereby raising the figure above 17mpg.
Experiment 2
Observation
The Clean Air Act requires various different blends of gasoline to be sold at different times of the year, based on pollution profiles as each blend is burned in automobile engines. "Summer gasoline" blends require the removal of some volatile organic compounds which can contribute to smog production when burned (citation). Winter blends do not have the same refining requirements. Gasoline blends with different refining requirements should have different energy content and fuel efficiency profiles. Conventional wisdom asserts that summer blend gasoline yields higher fuel efficiency.
Hypothesis
Summer blend gasoline should produce higher fuel efficiency readings during the time period in which it is sold.
Materials
- One Oldsmobile Intrigue GL (2000 year model with 3.5L V6 engine)
- 1100 gallons of 87 octane gasoline, purchased as needed in 7-15 gallon increments
- notepad
- pen
- snacks for driver
Over the span of 32 months, data was recorded at the time of gas fillup. This data consisted of the date, the amount of gasoline added to the tank, and the number of miles driven since the previous fillup. No special effort was made to control for driving style. No special effort was made to control for terrain, road type, weather, vehicle maintenance condition, or traffic conditions. No special effort was made to control for geographic area, and while the vehicle spent most of its time in the Cleveland Ohio area, it also was driven in Michigan, Indiana, West Virginia, Pennsylvania, New York, and Ontario. Driving speed varied based on location, based loosely on the posted speed limit. The gasoline tank was filled 79 times during the course of the experiment. The first data point was discarded because the date was not recorded.
Results
A scatter plot was used to show the average mileage for each tank of gasoline and the numerical day of year on which that tank was purchased.
There is no discernible trend based on date.
Conclusion
The data is unable to support the hypothesis. There are too many uncontrolled variables that affect vehicle mileage other than gasoline blend.