Cut Down on Car Emissions

Cars on road
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Greenhouse gases, responsible for global climate change, are emitted in large part from the combustion of fossil fuels like oil, coal, and natural gas. Most of the emissions from fossil fuels come from power plants, but second ranked is transportation. In addition to carbon dioxide, motor vehicles release particulate pollution, carbon monoxide, nitrogen oxides, hydrocarbons, and volatile organic compounds.

Maybe you have already adjusted many aspects of your lifestyle to reduce your carbon footprint, including installing LED lights, turning down the thermostat, and eating less meat. However, in your driveway sits glaring evidence of one source of greenhouse gas that you could not get rid of: your car. For many of us, especially in rural areas, bicycling or walking to school and to work may not be an option, and public transportation may simply not be available. Do not fret; there are still actions you can take to lower the pollution and greenhouse gas emissions you produce when driving.

Fuel Economy vs. Emissions

We generally assume a vehicle with better fuel economy will also release fewer harmful emissions, including greenhouse gases. The correlation generally holds true, with a few caveats. Decades-old vehicles were built under much more relaxed emissions regulations and can be prodigious pollution producers despite a relatively modest thirst for fuel. Similarly, you may be getting 80 miles per gallon on that old two-stroke scooter, but that smoke will contain much more harmful pollutants, much of it from partially burned gasoline. And then there are the cars with emission control systems releasing illegal amounts of pollution, like those finger-pointed during the infamous Volkswagen small diesel engine scandal.

The obvious place to start to reduce emissions, of course, is by choosing a modern vehicle with the best possible fuel economy. Models can be compared using a handy web tool put together by the U.S. Department of Energy (DOE). Be realistic about your needs: how many times a year will you really need a pick-up truck, sport-utility vehicle, or minivan? Performance is another fuel economy killer, but if you really want a sportier car, favor a four-cylinder model with a turbocharger instead of a larger six or eight (or twelve!) cylinder car. The turbo kicks in on demand, with the more frugal four cylinders doing the work the rest of the time.

Manual vs. Automatic

Not so long ago manual transmissions provided better fuel economy than automatic transmissions. It was a good excuse for those who love to row their own gears but modern automatic transmissions, which now have 5, 6, and even more gears, provide better mileage. Continuous Variable Transmissions (CVT) are even better at maintaining the engine’s revolutions at the right speed, beating even the most skilled stick-shift enthusiasts.

Older Car, Newer Car

Older cars were designed and constructed in the context of emission regulations that were much less restrictive than they are today. Much improvement has been made in the 1960s, with the development of the catalytic converter and fuel injection, but it wasn’t until the soaring gas prices in the 1970s that real fuel efficiency gains were made. Amendments to the Clean Air Act gradually improved car emissions starting in 1990, with important gains made in 2004 and 2010. Generally, a more recent car will have better technology to reduce emissions including electronic direct fuel injection, smarter electronic control units, lower drag coefficient, and improved transmissions.


You probably heard this one before: simply keeping your tires inflated to the proper level will save you in fuel costs. Under-inflated tires will cost you as much as 3% in fuel costs, according to the DOE. Maintaining proper pressure will also improve your stopping distance, reduce risks of skidding, rollovers, and blowouts. Check for the appropriate pressure on a sticker located in the jam of the driver-side door; do not refer to the pressure value printed on the tire sidewall.

Replace your engine air filter at the interval specified in your owner’s manual, or more frequently if you drive in especially dusty conditions. The dirtier your air filter is, the more fuel you will use.

Do not ignore lit check engine lights, even when you feel like the car is operating normally. Often the emissions control system is a fault, which means you are polluting more than usual. Bring the car to your mechanic for a proper diagnostic, it may save you from more expensive damage later on.

Car Modifications

After-market performance modifications abound in some types of cars – louder exhaust pipes, modified air intakes, reprogrammed fuel injection. All those features increase your engine’s fuel needs, so get rid of them or better yet don’t install them in the first place. Larger tires and suspension lifts need to go too. Roof racks and cargo boxes should be put away when not in use, as they severely affect fuel economy, especially on smaller cars. Empty your car trunk too, as it takes extra fuel to carry around that golf bag you never have time to get out, or those crates of books you’ve been meaning to drop off at the thrift store.

What’s Your Driving Style?

Driving behavior is another place where you can make a big difference in your emissions and fuel use without spending any money. Slow down: according to AAA, going 60 mph instead of 70 mph on a 20-mile commute will save you 1.3 gallons on average over the work week. Accelerate and stop gently, and coast while you can. Keep your windows up to reduce drag; even running the air conditioning requires less energy. Letting your car idle in the morning is unnecessary, uses fuel, and produces useless emissions. Instead, gently warm up your engine by accelerating smoothly and keeping a lower speed until your car reaches its operating temperature.