Traffic accidents involving motor vehicles are overwhelmingly the leading cuase of death by unintenional injury or adverse effects for the US population, accounting for almost half of such deaths. (Adverse effects include things like unexpected reactions to drugs.) Lots of information on death rates and leading causes of death are available on the web from the National Center for Injury Prevention and Control, whose web pages seem to be hosted by the Center for Disease Control. Check out the chart of deaths by unintentional injury and adverse effects for 1998, all ages (local copy).
Infants and older adults have high rates of death from various diseases and medical conditions, but amongst people aged 1-44, unintentional injury and adverse effects is the top cause-of-death category (see chart or local copy) and traffic accidents involving motor vehicles is the top cause of death within this category by a wide enough margin (56.8% of these deaths for 1998, see see chart or local copy) that this single subcategory of injury is more prevalent than any of the other major categories, including heart disease, HIV, malignant neoplasms, suicide, and homicide.
Amongst those aged 15-24, traffic accidents represent almost 3/4 of the injury and adverse effects deaths (see chart or local copy).
The point of all this is simply that automobile safety is extremely important. There are many risks in the everyday world that you cannot influence to any significant degree. You can't do a lot to minimize the risk of a terrorist bomb killing you or those that you care about, for instance, or to minimize the risk of a plane that you fly on crashing, or to prevent a building that you work in from collapsing during an earthquake, etc. However, it turns out that traffic accidents are one of the most prevalent risks you probably face, and it just so happens that you have the power to significantly influence it by choosing the vehicle you drive and its options wisely (not to mention driving safely, using seatbelts, not driving drunk or when excessively sleepy, not driving too fast, being alert, etc.). You can have a great impact on the likelihood of you or those you care about who might travel with you either dying or being severely injured, maimed, permanently disabled, etc.
Update (Sept 2001): Amazingly, I wrote those words above about terrorists, planes crashing, and buildings collapsing long before the 9/11/2001 terrorist attacks, which involved all three. Many Americans since that tragedy have been showing their support for the country and have been trying to participate in efforts to help in any way they can. In fact, the response of the American public has been rather overwhelming (in terms of blood donations, volunteering, flying flags, and just pay attention to the issues). This is admirable. However, it is unfortunate that more Americans (and the popular media) don't put as much effort and thought into automobile safety as they have into showing support for the country in recent weeks and thinking about airline safety.
Update (May 2002, text I wrote in the Sept update above with corrected numbers): The last figure I have seen was 3245 deaths on 9/11 from the terrorist attacks, including those from New York (under 3000) and from DC and the plane downed in Pennsylvania. While this is the most people to die in a single day on US soil since the civil war, the fact is that over 10 times as many people in the US die EVERY YEAR, YEAR AFTER YEAR, from motor vehicle trafffic accidents (13 times as many people in 1998 based on stats of 42,191 deaths). That means that EVERY MONTH is another 9/11/01-sized death toll! The vast majority of these deaths would be preventable if everyone would follow reasonable safe driving procedures, wear seatbelts, etc. Favoring important safety features like ABS, stability control, side air bags, and good crash test scores when making purchasing decisions would also go a long way to reducing deaths EVERY day.
It's mid-Nov., 2001. That means that more people have died since 9/11/01 in motor vehicle accidents than died on 9/11, plus died of anthrax poisoning, plus died in the recent New York airline crash. Hours upon hours of radio shows, TV shows, newspaper discussions, etc. have taken place over the past two months discussing in great details ways to minimize risks of future terrorist attacks, biological hazards, airline disasters, etc. The average US adult, who can personally do very little to minimize these risks, now knows quite a lot about these issues, but many are still completely ignorant about important issues of automobile safety over which they do have some degree of control. Many people think that having airbags poses a statistically greater risk than not having them. Many people don't know what stability control is, which vehicles offer it, or whether their vehicle has it. Many people don't realize how to drive correctly with anti-lock brakes. Many people think that not wearing a seatbelt is safer since they won't be as likely to be trapped in the car. Many people don't realize that driving while extremely tired and sleep deprived is at least as impairing as driving just over the legal intoxication limit and causes similar numbers of fatal accidents. Many people don't realize that over half of the fatalities from side impacts involve injuries to the head which could be prevented or made much less severe with side head airbag systems. If the media would concentrate a bit more effort on educating the public about these issues it would actually SAVE lives immediately.
Update (Dec. 2002): The Insurance Institute for Highway Safety released a report that agrees that auto safety does not get enough attention in the US relative to less frequent dangers (local cached copy).
Update (Jan. 2005): The recent earthquake/tsunamis from 12/26/04 have a deathtoll approaching 150,000, and like 9/11 are getting an unbelievable amount af press/worldwide-attention. Let's compare that to worldwide traffic fatalities. My first quick Google search attempt for [worldwide traffic OR auto OR automobile deaths OR "death toll"] produced an interesting article reporting WHO and World Bank estimates of 1.2 million traffic deaths per year worldwide (and increasing rapidly). That's nearly an order of magnitude more than the 12/26/04 natural disaster, which is the type of natural disaster that comes along only once every few decades. The article also states that traffic fatalities are now the leading cause of death in the developing world. Clearly the 12/26/04 events were horrible and much attention and aid is deserved. What's bad is the lack of corresponding (or greater) attention paid to automobile/traffic safety. See also my reminder e-mail to people that there are worse things than tsunamis.
Other health and safety related consumer info that I've collected.