Gov. Bill Haslam’s gas tax plan has gotten a unanimous endorsement from the Roane County Commission. Last month Haslam introduced the IMPROVE Act: Improving Manufacturing, Public Roads and Opportunities for a Vibrant Economy. It proposes to increase the state tax on gas 7 cents per gallon and on diesel 12 cents per gallon. The state’s current tax on gas is 21.4 cents per gallon and 18.4 cents per gallon on diesel. According to a January 2015 report by the Tennessee Comptroller of the Treasury, the gas tax was last raised in 1989. The report said the diesel tax was last raised in 1990.The Commission received a letter at its meeting from Roane County Road Superintendent Dennis Ferguson, who also supports the governor’s plan.