(Beaver Dam) Depending on which survey you accept, the average price of a gallon of regular unleaded is down 20-to-30 cents in Wisconsin, compared to last year at this time. Triple-A puts the Wisconsin average at $2.18-cents-a-gallon. For a vehicle with a 16-gallon gas tank, a savings of nearly five dollars for each fill-up is possible. Gas in Beaver Dam is as low as $2.19. The national average is $2.36 for each gallon as families leave on their Christmas vacations.