Iowa State University economist David Swenson said most Iowa motorists would pay less to cover a proposed 10 cents per gallon increase in the gas tax than they would to fix vehicle damage caused by bad roads. Swenson reportsthat if you drive 20,000 miles a year and average 25 miles per gallon, you would pay $80 a year in extra gas taxes. Driving 30,000 miles and averaging just 10 miles a gallon would mean paying an extra $300 a year. The current tax of 21 cents a gallon for regular, 19 cents for ethanol and 22.5 cents for diesel hasn’t changed since 1989. With gas prices low and the most recent elections past, Gov. Terry Branstad and some lawmakers are talking about taking action to cover an estimated $215 million to $230 million shortfall in road maintenance cash.