The U.S. government supports research on hybrid cars.

A 2007 law provided money for work on plug-in hybrids and on better batteries. It even called for a college contest to develop plug-ins. It also encouraged the use of hybrids by the government.

This kind of support for hybrid cars may well increase over the coming years.

Gasoline is the most common fuel used today in hybrid cars. Car companies are looking at other fuels for possible use.

A good alternative fuel might cost less, cut pollution more, or be better at reducing the overall use of oil. Alternative fuels are already used in some traditional cars, buses,or trucks.

One alternative fuel is ethanol. Another is natural gas. Yet another is liquefied petroleum gas (propane), often called LPG for short. In some countries, LPG is cheaper than gasoline. The Hyundai company planned to start selling an LPG hybrid in 2009 in South Korea.

Car companies are also studying the use of a so-called flex-fuel engine in hybrids. Flex-fuel engines are flexible. They can run on more than one kind of fuel.
In addition, car companies are looking into the use of fuel cells in hybrids. Fuel cells use hydrogen to make electricity. The only thing they give off in the process is water!

Toyota’s experimental FCHV (Fuel-Cell Hybrid Vehicle) has a fuel cell instead of an internal-combustion engine. One problem with fuel cells is that right now hydrogen is not widely available. Another problem is that fuel cells so far tend to cost a lot.

The first electric cars were made in the 19th century. A few are still made today. Instead of a gas tank, they usually have batteries, which store electricity. Instead of an internal-combustion engine, they have an electric motor. The motor uses electricity from the batteries to produce a turning action. This action
is used to turn the car’s wheels. Electric cars have some strong points. They are quiet and clean. Because they run on electricity, they cause little or no pollution.

Drawbacks of Electric Cars

Electric cars have never really caught on, though.

One problem is the batteries. They’re heavy, and they take up a lot of space. Also, until recently the batteries haven’t been able to hold enough energy to let an electric car go as far or as fast as traditional cars can. Some car companies made a small number of electric cars and pickup trucks in the 1990s. The
cars had a top speed of around 80 miles (130 kilometers) an hour. They couldn’t go much farther than 100 miles (160 kilometers) before the batteries had to be recharged.

Recharging the batteries takes a lot of time. Usually you have to find a way to plug the car into the public power system. If you can’t recharge at home, finding a place to recharge can be hard. Recharging stations are few and far between. Recent advances in batteries have made the situation a little better.

Still, electric cars are rare in the United States.

Cars have been around for more than 100 years. They have changed a lot in that time. Today’s cars are faster and more reliable than those of long ago. They are also safer and more comfortable. One thing has not changed: the way most cars work. Most cars of the past ran on fuel made from oil. That’s still true today. Usually the fuel is gasoline (often called “gas”for short). Sometimes it is diesel fuel. Both come from oil.

The Trouble with Oil

Oil is a very good source of energy, but using it has problems. One problem is that oil is not a renewable resource. Once it’s used, it’s gone. If people keep on using it, eventually the world will run out of oil. Meanwhile, as oil gets less plentiful, fuels made from it will probably get more and more costly over time.
Another problem is that using fuels made from oil releases certain gases into the air. Some of these gases can be bad for people’s health. Many scientists say that some of the gases are changing Earth’s climate.

These are serious problems because the world has a huge number of vehicles, and every year more are produced. In 2007, for example, more than 50 million cars were made. If you include trucks and buses, the number of new vehicles made that year gets even bigger.

One way to deal with these problems is to use less oil. This is where hybrid cars come in. They get their power from electricity as well as from gasoline (or
diesel). As a result, they use less gas.

Many hybrids use a special trick to avoid wasting energy.

When a car slows down by braking, the energy of the wheels has to go somewhere. In traditional cars it turns into heat in the brakes. In other words, it goes to waste. Many hybrid (and electric) cars put much of this energy to good use. They capture the energy and send it to the motor, which then works as a generator and makes electricity. The electricity can be stored in the batteries, ready for later use.

This useful way of making electricity from the energy of the wheels is called regenerative braking.

The Prius was first sold in the United States in 2000. Seven years later it became the first hybrid to rank among the top-ten bestselling cars in the United States.

Toyota brought out hybrid versions of its Highlander and Lexus sport utility vehicles (SUVs) in 2005. In 2006, Toyota came out with hybrid versions of its popular Camry and Lexus sedans. By spring 2007 the company had sold more than 1 million hybrids around the world.

A year later, total sales of the Prius alone passed 1 million. Honda stopped making its original Insight in 2006. It had more success with a hybrid version of its very popular Civic. This hybrid, launched in 2003, was about the size of the Prius.

In 2009, Honda came out with a new, slightly larger version of the Insight. In 2004, Ford brought out the first hybrid made by a U.S. company. The car was a hybrid version of the Escape SUV. It was actually the first hybrid SUV in the world.

In the following years, hybrid versions of other makes of cars also came on the market.

Hybrids became available in the United States a few years later than in Japan.

Today, the number of hybrid models on the U.S. market is still far smaller than the number of traditional car models. Even so, more and more Americans are buying hybrids. In 2007, they bought more than 350,000 new hybrid vehicles.

This was 38 percent more than in 2006.

Oil is a major cause of pollution. The same is true of the fuels made from it.

For one thing, oil is sometimes accidentally spilled into the environment. This can harm plants and wildlife. Another problem arises when oil is refined, or made, into fuels. This process releases pollutants into the environment.

Still another problem occurs when fuels such as gasoline are used. Burning them puts pollutants into the air. In fact, the U.S. Environmental Protection Agency (EPA) says that driving a car “is probably a typical citizen’s most ‘polluting’ daily activity.” Gases that go into the air when gasoline is burned can be a major cause of air pollution.

Cars put various substances into the air. One of them is carbon monoxide. This gas can cause health problems. Other gases called nitrogen oxides can lead to
smog, which can also be harmful to people’s health. Substances called hydrocarbons are another potential cause of smog. Cars also produce large amounts of so called greenhouse gases, such as carbon dioxide. Many scientists think that greenhouse gases in the air are making the world’s climate warmer. This
climate change is known as global warming.

Pollution Limits
In the United States there are laws that put limits on certain pollutants
from cars. One of them is the Clean Air Act of 1970. Another is the Clean
Air Act of 1990, which made refineries produce gasoline that burns more
cleanly. States such as California also have limits on certain pollutants.

Grading Cars for Pollution
Like traditional cars, hybrids burn fuel. They generally use less, however, and so they cause less pollution.

For this reason, hybrids usually score well when the EPA grades cars on their environmental effects. The grades range from 0 to 10, where 10 means best, or cleanest. For example, the 2009 Nissan Altima Hybrid, a midsize car, scored 9 for greenhouse gas and 9.5 for air pollution. By contrast, the 2009 Lexus SC430, a small non-hybrid from Toyota, scored only 5 for greenhouse gas and got similarly low marks for air pollution.

Using less fuel can help the environment. Many people would like to use less for another reason as well.

Gasoline costs money, and the price tends to keep going up. Sometimes it does go down. But over the long term, the price tends to gradually go up. A common way of telling how well, or efficiently, a car uses gasoline is to look at its fuel economy. This is the number of miles it can go on 1 gallon. (A mile is about 1.6 kilometers.)

Partly this depends on how the car gets its power. Hybrids can use less gasoline because they get some of their power from electricity. Mileage per gallon also depends on the car’s weight. It takes more energy to move a heavy car than a light one. The shape of the car is another factor. A moving car pushes against the air, and this takes energy. Some shapes have less “drag.” They slip through the air more easily than others. Factors like these explain why different cars—even different hybrids—don’t all get the same number of miles per gallon.

Hybrids, such as those
being driven in New York
City, usually use less
gasoline in city than in
highway driving.

Grading Cars for Fuel Use
If you want to compare different cars, mileage figures from the EPA can help.

The agency measures all cars the same way. It found that the 2009 Toyota Prius could do 48 miles per gallon (20 kilometers per liter) in city driving and 45
miles per gallon (19 kilometers per liter) on the highway. Traditional cars usually get better mileage on the highway than in the city. The Prius does better in the city because it uses its electric motor more there.

In the United States the average fuel usage of new cars has to be better than a certain level. A 2007 law said this level will rise to 35 miles per gallon (14.9 kilometers per liter) by the year 2020.

Hybrids do have some disadvantages. For one thing, they tend to cost more to buy than similar traditional cars. Of course, they do save money for their owners by using less gasoline.

Hybrids are often smaller and less powerful than similar non-hybrid cars. This can be a drawback for people who like big, powerful cars. Some hybrids do have big engines. These “muscle” hybrids can deliver a lot of power, but they don’t save much on gasoline. The hybrid version of Toyota’s 2009 Highlander SUV got just 25 miles per gallon (10.6 kilometers per liter) on the highway, according to the EPA. The non-hybrid version was almost good, averaging 23 to 24 miles per gallon (9. 8 to 10.2 kilometers per liter).

Expensive Batteries and Service: The batteries in a hybrid are heavy. Their weight increases the amount of energy needed to make the car go. Also, they take up a lot of space. They make the car less roomy. In addition, they are very expensive. They are very reliable and should last a long time, but if hybrid batteries ever need to be replaced, the cost will be high.

Hybrids are complicated cars: Fewer service people know how to fix them. Repairs may sometimes cost more than for traditional cars. But this situation may change as more and more hybrids appear on the road.

Lowering the Cost: Various programs intended to boost hybrid use can help lower the cost of hybrid cars. Some hybrid buyers get savings on taxes. Hybrid owners may pay less for insurance. In some areas, hybrid drivers can park for free or at a reduced rate. Car makers are trying to make the batteries in hybrids smaller and lighter.