When gasoline cost less than 50 cents a gallon, many people had large automobiles that got low gas mileage. Some people liked the feel of a large car on the road. Others thought large cars were more comfortable and luxurious.
When the price of gasoline suddenly increased in the 70s, people began calling the large cars "gas guzzlers." Small cars became more economical and more practical. Soon there were fewer large cars on the highways.
Gas mileage is the number of miles a car travels for each gallon of gasoline the engine uses. The second law of motion explains why a large car uses more gasoline than a small one. It takes more energy to move a car with a mass of 2,000 pounds than it does to move one with a mass of 1,600 pounds.
Gasoline is used much faster in the larger car. Gasoline is made from oil, which is being used at a rapid rate. It makes sense to conserve oil resources. In addition, gasoline exhaust causes air pollution. Driving a car with better gas mileage benefits air quality.
Efforts are being made to develop cars that use other types of fuel, such as etanol and solar power. The resources for these fuels are renewable. For example, plant fiber is used to make etanol that is suitable for automobile engines. Solar-powered cars are practical in areas that have the most exposure to the sun.
