Green cars come in many shapes, sizes, and types: gas, diesel, hybrid, bioethanol, natural gas, ethanol and fuel cell. To determine which car is better for the environment, your wallet, and your lifestyle, is quite complex as numerous factors need to be considered. Read on to learn what factors to consider in purchasing your next Green Vehicle...

What Makes A Car 'Green'?

What makes a car “green” is its level of greenhouse gas emissions as well as its fuel economy (miles per gallon or MPG). In the United States, road transportation is the second largest source of greenhouse gases, with carbon dioxide (CO2), methane (CH4) and nitrogen oxides (NOx) as the biggest offenders leading to global warming. 

MPG or CO2?

Fuel economy and CO2 emissions are related: a small car, such as the smart fortwo, has a very good MPG, with 33 mpg in the city and 41 on the highway. It uses less gas (i.e. is fuel-efficient), and therefore emits less CO2. But the correlation does not extend to other greenhouse gases and air pollutants, therefore a smaller, more fuel-efficient car doesn’t necessarily mean a “greener” car. More specifically, nitrogen oxides (NOx) emissions need to be carefully looked at, as NOx are hazardous, noxious pollutants causing respiratory problems, among many others. According to greenercars.org, “motor vehicles account for about one-third of nationwide NOx emissions. […] cars and light trucks are […] a major source. NOx has also been one of the most difficult pollutants to get out of our air.”

How Do Hybrids Score?

Hybrid cars boast high fuel-efficiency as well as reduced CO2 and NOx emissions, which is why they are the favored green cars on the market. According to Whatgreencar, “most gasoline-hybrids reduce lifecycle greenhouse gas emissions (per mile) by around 25% compared to an equivalent gasoline car. All non-carbon emissions are also significantly reduced for a gasoline-hybrid passenger car as compared to a conventional gasoline vehicle. These include typical reductions in carbon monoxide (CO), non-methane hydrocarbons (NMOG) and nitrogen oxides (NOx) of over 70%.”

Super-Ultra-Low-Emission Vehicles

Last piece of advice: opt for a SULEV II, i.e. a Super-Ultra-Low-Emission Vehicle, phase II.  This is a stringent California standard which includes significantly lower NOx emissions and more durable control systems than other lower standards. The only two more stringent standards, after a SULEV II, are PZEV (Partial Zero Emission Vehicle) and ZEV (Zero Emission Vehicle), which only all-electric vehicles and fuel cell vehicles powered by hydrogen can boast. The issue with PZEV and ZEV is that they are not available nationwide and that they have other restrictions.

The Bottom Line

There are many options to consider when selecting a green car. Fuel consumption, carbon and nitrogen oxide emissions, refueling options, passenger and luggage space, comfort, interior options & accessories, and last but not least; price. Following two simple rules-of-thumb, however, can make the task easier:

1. the smaller the car, the better, as cars with less mass tend to have better fuel economy; and

2. hybrid vehicles are currently more fuel-efficient, less polluting and more widely available and operable than other types of green cars.

For more information on green cars, visit whatgreencar.com and greenercars.org.