Fuel economy

Fuel consumption Measured in number of miles the car will travel on 1 gallon of petrol. In science we should measure in km per litre. However, all available data are in miles per gallon (mpg) The mpg are worked out for an average journey including fast motorway driving and slow town driving.

Energy transfer Fuel is a concentrated source of energy. In the car engine the fuel is combined with oxygen. The energy is transferred to the wheels of the car. Some engines are more efficient than others. This means that they transfer more energy to the useful function (e.g. movement) and less as heat and sound.

Designing an energy-efficient car You are starting out in car design. You are concerned about the environment and you want to reduce the amount of fuel used. You need to consider what factors affect the number of miles a car will go on each gallon of petrol. Assume that engines are equally efficient.

Factors to consider Type of fuel (petrol/diesel). Size of the engine (litres). Mass of the car (kg). Power of the engine (acceleration - time to change speed from 0-60 mph). Shape of the car (make).

Fuel economy in different cars

Draw scattergraphs to compare miles/gallon with each factor

Tips There are only two types of fuel. Filter the fuel column so that you can compare the factors (mass, engine size, acceleration, make) for petrol cars then diesel cars.

Excel support To filter, select all data (click empty cell in top left next to A column label). On tool bar select ‘Data’, then ‘Filter’. Select ‘Autofilter’. Select the arrow at the top of the fuel column and choose ‘Petrol’.

Excel support Sort the mpg column in ascending order (select all: ‘Data’: ‘Sort’: ‘Column E’: ‘Ascending’). Highlight mpg column and then (holding down ‘Control’ key) highlight another column. Click the chart icon. Choose ‘XY Scatter’. Follow the wizard. Label the chart.

Research There has been much publicity about the Honda Insight. Honda claim that this car with its new engine design will give a fuel consumption of over 70 mpg. Use the Internet to find out why this engine is so different.