Car driving

Car driving

Cars are as American as apple pie and our affection for the automobile has staggering environmental implications. In 1994, the last year the government conducted a national survey, residential vehicles in the US traveled 1.8 billion miles—enough to get to the moon and back more than 3,700 times.[1] While fuel consumption and emissions are likely the biggest environmental issues plaguing our vehicular habits, they're not the only ones. Following our motorized trails are also concerns over water contamination, waste production, and wildlife casualties.

Fuel and emissions

To feed our appetite for the freedom of a car, we use more than 100 billion gallons of gasoline each year. If that fuel were stored in a tank the size of a football field, the walls would have to be nearly 50 miles high.[2] Every gallon of gasoline burned releases 20 pounds of carbon dioxide, making the transportation sector responsible for about a quarter of overall US carbon dioxide emissions.[3] And because no combustion is perfectly clean, cars are also a primary source of local air pollution. However, driving less aggressively, and maintaining engine and tire pressure, can improve fuel economy by close to 15 percent, allowing a US driver an additional 1,700 miles using the same amount of gas each year.[4]

Water contamination

The various pollutants released into the air by automobiles can settle in bodies of water with dire results. For example, when a lake is contaminated with nitrogen, oxygen levels drop due to excessive algae growth and, as a result, aquatic life can die.

The improper disposal (dumping down gutters and storm drains, for example) of motor oil, antifreeze, and other toxic substances associated with routine automobile upkeep is a major contributor to water pollution. Groundwater contaminated by one quart of oil can affect up to 250,000 gallons of drinking water.[5]

Wildlife casualties

Cars and the roads they travel on can be lethal to animal habitats. In the United States, more than 190 million motor vehicles (cars, trucks, buses, and motorcycles) are operated daily. More than one million animals are hit and killed by these vehicles each day. That amounts to annual “roadkill” casualties of about 400 million, twice the number killed as “game” by hunters.[6]

Although domestic roadways are increasingly constructed with natural habitats in mind, the US is still far behind Europe where this practice has been going on for decades. For example, a roadway in Slovenia has a special viaduct designed for the safe passing of bears, lynxes, and wolves, and overpasses in Switzerland feature ponds for amphibians. The Humane Society offers advice on how to avoid animal collisions.

Solid waste

Most of the 27 million automobiles that are “retired” each year are recovered for recycling. According to the United States Council for Automotive Research (USCAR), 80 percent of a car can be recycled. The remaining non-recyclable parts known as auto shredder residue (ASR) consists of fabric, paper, plastic, wood, rubber, glass, metal, dirt, and other materials. Five million tons of ASR enters landfills each year.[7]

Additionally, 27 million scrap tires are estimated to have entered landfills or monofills in 2003. However, landfill-bound scrap tires represent only 9.3 percent of total scrap tires (290 million were generated by the US in 2003). The remaining tires are recycled and reused for a wide array of purposes, including civil engineering projects and making new products, such as playground surfaces.[8]

Roadside littering

It’s estimated that while 45 percent of roadside trash comes from unsecured or uncovered loads on trucks, the remaining 55 percent is generated by drivers intentionally discarding garbage directly from their cars. Fifty-one percent of roadside litter comes from food and beverage packaging.[9] It takes over 700 years for plastic soda bottles tossed from a car to decompose and between one and five years for cigarette butts (one of the most littered items) to break down.[10][11]


Following the oil crisis of 1973, Congress in 1975 enacted a regulation called Corporate Average Fuel Economy (CAFE) to improve the fuel efficiency of personal vehicles sold in the US. CAFE has garnered criticism from all sides: environmentalists argue that the standard isn't high enough, free-market advocates claim it limits choice and potentially decreases safety by encouraging the use of lighter vehicles. Still others feel it unfavorably benefits foreign automakers, who tend to produce smaller, more fuel-efficient cars.

Automakers in particular have criticized CAFE. Bob Lutz, Vice Chairman of Product Development at General Motors, declared that forcing automakers to sell smaller cars to improve fuel economy is like “fighting the nation’s obesity problem by forcing clothing manufacturers to sell garments in only small sizes.” The Alliance of Automobile Manufacturers—an industry group that represents all major automakers but Honda—lobbies to reform or scrap CAFE.

Whether CAFE has improved fuel economy is a topic of considerable debate. Since 1980, average fuel economy has remained relatively flat. At the same time, however, automobiles have become safer, quieter, larger, heavier, and considerably more powerful.

Recently, California and other states have sued the Environmental Protection Agency (EPA) to regulate CO2 emissions from automobiles beginning in 2009—a de facto regulation of fuel economy. Automakers are countersuing.

Related health issues

Aside from the global-warming gas carbon dioxide, three major pollutants emitted by automobiles—hydrocarbons, carbon monoxide, and nitrogen oxide—also pose dire risks to human health. Specifically, when hydrocarbons and nitrogen oxide mix in sunlight and high temperatures, ground-level ozone is created. This leads to coughing, wheezing, and eye irritation, and can result in chronic lung problems. Carbon monoxide decreases levels of oxygen in the bloodstream and affects mental and visual functions.

Automobile emissions in the United States have been regulated since the 1966 model year, following research that linked car exhaust with smog in Los Angeles. At the time, cars emitted nearly 13 grams per mile of hydrocarbons (HC), 3.6 grams per mile of nitrogen oxides (NOx), and 87 grams per mile of carbon monoxide (CO). Today’s standards are 0.25 gram per mile of HC, 0.4 gram per mile of NOx, and 3.4 grams per mile of CO.[12]

Pollution aside, research suggests that driving itself can be unhealthy: excessive time spent behind the wheel (which leads to stress and inactivity) can cause elevated blood pressure, headaches, and mood swings. Additionally, vibrations from the road and from sitting in place for long stretches are harmful to back and neck. And even carpoolers are prone to the unhealthy side effects of driving; stiff necks and sore joints plague commuters crammed into the backseats of cramped cars.


  • automotive fuel economy: Fuel economy in cars is important because carbon dioxide emissions are directly related to the amount of fuel burned. Mpg, or "miles per gallon," is the way most Americans measure fuel economy. (Europe, for example, uses l/100km or liters of fuel per 100km traveled.) To measure your fuel economy, fill your tank and reset the odometer. At your next fill-up, divide the miles traveled by the amount of fuel needed to refill the tank.For the 2008 model year, the EPA has updated its fuel economy test to reflect today's higher speeds, increased use of air conditioning, and other factors. In many cases, the published "window sticker" mpg values will be lower.
  • monofill: A monofill is similar to a landfill in design (a giant bathtub built into the ground) but contains no raw waste, only incinerator ash. The bottom of a monofill is lined with two giant sheets of plastic.

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