SUV sales are rising as gas prices fall. A new study by the University of Michigan Transportation Research Institute shows the average fuel economy on new cars sold in November dropped by one-tenth of a mile per gallon. Researchers say that continues a trend that began in August of last year. New cars sold in November still averaged about 25 miles a gallon. Earlier this week, Ford projected its SUV and pickup truck sales to grow as consumers take advantage of cheaper fuel prices.