Hybrid vehicles, which combine a gasoline engine with a battery-driven electric motor, have garnered sizable government subsidies on the strength of their fuel economy. But the vehicles’ real-world performance is less impressive than previously thought, according to mileage calculations recently adopted by the U.S. Environmental Protection Agency.

For the first time since 1984, the EPA has adjusted the method of estimating the fuel efficiency of new cars and trucks to account for faster driving speeds, aggressive acceleration, air conditioning, cold starts and stop-and-go traffic. The EPA mileage ratings are the only ones that can be used by automakers on vehicle window stickers.

Under the new formula, the mileage estimates for gas-electric hybrids drop the most, decreasing by 20 percent to 30 percent for city driving and 10 percent to 20 percent for highway driving. In contrast, the mileage estimates for most conventional vehicles decrease 12 percent for city driving and 8 percent for highway driving.

Since the 1970s, the mileage formula assumed top speeds of just 60 miles per hour and factored acceleration as 3.3 miles per hour each second. Currently, however, more than 25 percent of driving exceeds 60 miles per hour, and actual acceleration rates typically add 10 to 12 miles per hour each second.

Congress ordered the change in testing methods in 2005.


What do you know about mercury?

1. The source of most mercury in the atmosphere is:

A. Coal-fired power plants.
B. Surface and undersea volcanoes.
C. Soil and rock erosion.
D. Automotive exhaust.

2. The volume of mercury releases in Michigan related to human activity is:

A. 4.6 tons per year.
B. 10 tons per year.
C. 2.3 tons per year.
D. 115 tons per year.

3. The Environmental Protection Agency has concluded that the average IQ impairment of children born to mothers who, while pregnant, consumed fresh water fish exposed to power plant emissions of mercury is:

A. 0.009 of an IQ point.
B. 5 IQ points.
C. 10 IQ points.
D. 50 IQ points.

4. Blood tests administered by the Centers for Disease Control found that mercury levels in blood have:

A. Increased in recent years.
B. Decreased in recent years.
C. Stayed the same.

5. In recent years, the industrial use of mercury in the United States has declined by:

A. 25 percent.
B. 10 percent.
C. 75 percent.
D. No change.

6. The percentage of mercury deposited annually in Michigan from the emissions of in-state utilities is:

A. 10 percent.
B. 2 percent.
C. 25 percent.
D. 5 percent.

For more information go to http://www.mackinac.org/archives/2006/s2006-04.pdf.


Answers: 1. B (Surface and undersea volcanoes); 2. C (2.3 tons); 3. A (0.009 of an IQ point); 4. B (Decreased in recent years); 5. C (75 percent); 6. B (2 percent).