If airbags are so safe, why doesn't my car have more?

Technically, there's no upper limit to the number of airbags you could place in a vehicle. A car could be designed with every interior surface ready to inflate during impact; however, that vehicle would be very expensive and very heavy. Cost and weight -- those are the two main limits to the use of airbags.

The installation of airbags costs money for both the materials and labor. Replacing an airbag that has already been deployed can cost anywhere from $500 to several thousand dollars. They cost significantly less when they're initially installed at the factory, but the cost adds up quickly as more and more airbags are added. For example, the side airbag option on a 2006 Ford Fusion adds almost $600 to the final cost of the car [source: CBS News].

Extra weight is another problem. Increased weight reduces fuel mileage. The U.S. Environmental Protection Agency estimates that each 100 lbs. of weight added to a car reduces mileage by two percent [source: Fueleconomy.gov]. While automakers don't typically release information about the weight of individual components, and an individual airbag doesn't weigh very much, multiple airbags can significantly increase overall vehicle weight. If you consider the airbag itself, the chemical propellants needed to inflate it, the wiring and sensors, plus the enclosures for all the components, you can see that filling a car with a bunch of airbags would hurt your fuel economy.

Sure, airbags may make your car slower and heavier, but there some definite advantages. We'll explore those on the next page.

There's really no debate -- airbags save lives and reduce the severity of injuries. Data based on crash testing and actual, real-world crashes, as well as studies by the Department of Transportation and the Insurance Institute for Highway Safety show that airbags improve safety [source: Insurance Institute for Highway Safety]. There's still a strong undercurrent of opposition to airbags, just as there was for mandatory seatbelts, but the data doesn't lie.

That's not to say that airbags are perfect. If used improperly, they can cause injury or death. Children in car seats should not ride in the front seat if the vehicle is equipped with an airbag, and drivers generally should not sit within ten inches of the steering wheel. Since 1990, 290 airbag-induced deaths have occurred; in the same time frame, however, airbags have saved more than 27,000 lives [source: Insurance Institute for Highway Safety]. Side airbags are even safer -- no one has ever been killed by one. Even in the worst cases (which can be counted on one hand) they only cause minor injuries. In addition, modern front airbags have a safer, two-stage design. In low-speed collisions, they inflate with less force, reducing the chance of injury if a child or smaller person is in the front seat.

The cost-effectiveness of airbags remains a topic of extensive debate. Several studies have attempted to tabulate the cost of producing and installing airbags, the cost of fuel associated with the extra weight and the cost of replacing used airbags. That total cost is then compared to a numeric figure representing the economic cost of deaths and injuries. The number that comes out ahead seems irrelevant when someone you know was saved from serious injury or death.

Indeed, airbags can even help save you money. Many insurance companies offer discounts for vehicles with certain safety features -- including airbags. This may seem counterintuitive, since the airbags add to the cost of repairing the vehicle. In fact, that extra cost often means the vehicle will be written off instead of repaired. Insurance companies also pay to cover medical bills resulting from injuries, and those costs far outweigh the airbag replacement price.

For more information about airbag safety and development, follow the links on the next page.