Americans have driven cars for more than 100 years. Throughout this time, cars have become a major part of the American lifestyle. Most U.S. families own at least one car. This may be due to the limited mass- transit options in many parts of the country. And in some places, weather conditions make walking or bicycling year-round difficult. There are 136 million passenger cars in the United States. About 97 percent of them rely on the internal combustion engine (ICE). ICE cars and trucks use 50 to 70 percent of oil produced in the country. They use so much because their engines are inefficient. But, the engine isn’t the only problem. Some people prefer fast sports cars, heavy, powerful trucks, or sport-utility vehicles (SUVs). Moving fast or pulling heavy weight uses additional fuel. So, these powerful vehicles are even more inefficient. Automakers say they would build more efficient vehicles if they knew that more people would buy them.
When fuel is inexpensive, fuel efficiency is not a major concern for most drivers. However, fuel prices have increased in recent years. This is partly because the United States largely depends on imported oil. Yet, much of the world’s oil is located in politically unstable countries. So, the United States may not always be able to obtain the amount of oil it currently consumes.
In addition, ICE vehicles cause environmental problems. Their exhaust contains unburned or partially burned fuels. These emissions are poisonous and contribute to smog. ICE vehicles also emit other harmful gases. For these reasons, consumers and car companies have shown interest in alternative cars. Some alternatives, such as electric cars, have been around for many years. Others, such as hydrogen fuel-cell cars, are still being developed. Despite their differences, alternative cars share a common goal. They provide more efficient transportation with less harmful effects.
When gasoline prices rise, many people pay closer attention to the fuel economy of their vehicles. Fuel economy is measured by how many miles a vehicle can travel using one gallon (4 L) of fuel. The U.S. government publishes a list of fuel economy ratings for cars. However, many drivers report that they get fewer miles per gallon than the listed amount. This is because the rating system does not reflect how most people drive.
Fuel economy ratings assume people drive no more than 60 miles per hour (97 km/h). And, they assume people accelerate slowly, going from 0 to 60 miles per hour in 18 seconds. However, the average driver accelerates about five times as quickly. Weather also affects fuel economy. Federal standards measure fuel economy at 68 to 86 degrees Fahrenheit (20 to 30°C), without air conditioning. In most places, temperatures are well outside that range.
Finally, more energy is needed to move heavy weight. Today, the average U.S. adult weighs about 25 pounds (11 kg) more than the average adult in 1960. Compared to the yearly amount of gasoline that U.S. passenger vehicles burned in 1960, they burn an additional 938 million gallons (4 billion L) today. That extra gasoline would be enough to fuel nearly 2 million cars for a year!