a. Cars are becoming more fuel efficient, and therefore get more miles to the gallon. b. The winter is exceptionally cold. c. A major discovery of new oil is made off the coast of Norway. d. The economies of some major oil-using nations, like Japan, slow down. e. A war in the Middle East disrupts oil-pumping schedules. f. Landlords install additional insulation in buildings. g. The price of solar energy falls dramatically. h. Chemical companies invent a new, popular kind of plastic made from oil