| Vol. 6 | No. 3 | Summer 2004 |
 |
Close to Home
Clean Cars A to Z |
Thanks to this year's record gas prices, clean, fuel-efficient cars are in the news, but you may have had a hard time deciphering the alphabet soup of clean-car terminology. To help you make smart vehicle choices, we offer this brief summary of some important technologies and regulations.
Fuel Economy
Today's car and truck fleets must meet minimum Corporate Average Fuel Economy (CAFE) standards. Cars must achieve an average fuel economy of 27.5 miles per gallon (mpg); light trucks and SUVs must average 20.7 mpg today and 22.2 mpg by 2007.
Variable valve control (VVC) technology improves fuel efficiency by adjusting the operation of an engine's valves depending on engine speed and power demands. Several automakers offer VVC technologies; Honda's VTEC engine is an example.
Continuously variable transmissions (CVTs) and dual-clutch transmissions (DCTs) are more efficient and improve engine operation compared with conventional automatic transmissions. Audi, Honda, Nissan, Saturn, and Toyota offer CVT technology; Audi's direct shift gearbox (DSG) is an example of DCT technology.
General Motors' new Displacement on Demand (DOD) system is a type of cylinder deactivation technology that turns some engine cylinders off when power demands are low. Chrysler and Honda also plan to produce vehicles offering cylinder deactivation.
Vehicle Tailpipe Emissions
A new set of federal emission standards known as Tier 2 will hold all passenger cars and trucks to the same set of standards beginning in 2009. Tier 2 currently encompasses 11 emission categories, or "bins," ranging from Bin 1 (cleanest) to Bin 11 (dirtiest). Automakers can sell vehicles in different bins as long as they meet the fleetwide average of Bin 5.
Bin categories are not used for vehicles sold in California, Maine, Massachusetts, New Jersey, New York, and Vermont, which have even more stringent emission requirements. (Connecticut is also expected to enact these requirements.) At a minimum, vehicles in these states must qualify as a low-emission vehicle (LEV). Additional categories, from cleaner to cleanest, are ULEV (ultra low-emission vehicle), SULEV (super ultra low-emission vehicle), PZEV (partial zero-emission vehicle), and ZEV (zero-emission vehicle).
Several vehicles on the market today surpass the Bin 5 average (or qualify as LEVs or better). For example, some hybrid-electric vehicles (HEVs), which combine a gasoline engine with a battery-powered electric motor, meet Bin 3 emission standards and offer significantly better gas mileage than conventional vehicles. The Honda Civic Hybrid, Honda Insight, and Toyota Prius are the only mass-market HEVs available today, but the Ford Escape Hybrid, Honda Accord Hybrid, Lexus RX 400h, and Toyota Highlander Hybrid are slated for release during the next year--an important development here being the introduction of hybrid technology to SUVs. GM and Nissan also plan to introduce HEVs between 2006 and 2007, and Ford plans to release additional models as well.
The Road Ahead
Vehicle manufacturers continue to make strides in fuel-efficient technology and emission performance, and UCS is working to achieve a zero-emission automotive future. It should be noted, however, that automakers might not be using technologies to their full potential, so it is up to consumers to separate the truth from the hype. When the time comes for you to buy a new car, look for the model with the lowest emissions and highest fuel economy available that fits your needs and budget.
For more information about the technologies mentioned in this article, visit the Advanced Vehicles section of our website.
Also in this issue of Earthwise:
Dialogue
I've heard that wind turbines
kill birds. What can be done
to avoid it?
