The average fuel economy of new cars and trucks sold in the U.S. last year dropped to the lowest levels since 1980, according to a new report by the U.S. Transportation Department. President Bush’s energy plan released yesterday calls for a review of fuel-economy standards once the National Academy of Sciences completes a study of the topic in July. But greenies aren’t hopeful about the study because its authors include several people who worked for the auto and oil industries but no environmentalists. The energy plan also recommends a tax credit for consumers who buy gas-electric hybrid cars, but it doesn’t specify how large the credit should be.