First, the good news. As a result of regulations in the 1970s and the introduction of emission control technology (particularly the catalytic converter), emissions of carbon monoxide, hydrocarbons, and nitrogen oxides from U.S. cars have decreased to just 60-90% of 1970 levels.

Now, the bad news. Despite this technological progress, air quality has improved only slightly. How could that be?

A massive increase in car use: more people driving more cars on longer trips.
Since 1970, vehicle miles traveled have increased approximately 150 percent while the U.S. population increased only about 40 percent. Today, there are approximately 200 million cars in America, and over 700 million vehicles worldwide. If car numbers keep increasing at the present rate, there will be more than a billion on the road across the world by 2025. Vehicles are now driven two trillion miles each year in the United States, and there are more cars than adults.

What are the dots to connect to get a picture of “cars and the environment” trends?

  • Driving a private car is a typical citizen’s most air polluting activity.
  • Americans spend, on average, an hour per day in the car, and collectively over 8 billion hours per year stuck in traffic.
  • The 2000 census revealed that 3 out of 4 workers drive to work alone.
  • Each single family household generates approximately ten vehicle trips per day.
  • Less than 5 percent of the population uses public transportation.
  • Health care costs due to transportation pollution total over $60 billion per year.

The Most Important Environmental Choice

Given all this driving, it’s important to consider that of the many decisions you make as a consumer, car choice will have the greatest impact on the environment (according to the Union of Concerned Scientists).

Your choice when buying a new car is a vote to the carmakers, who are making decisions about today’s cars that extend well into the future. When a vehicle is designed, that model’s design stays the same for about five years. Each vehicle produced during those five years is going to stay on the road—roughly with that fuel efficiency and pollution level—for 12 to 15 years. Conclusion: buy the cleanest car you can, and drive less.

Buying a hybrid car tells the automakers that there’s definitely a market for greener cars.