Input: Relationship: 'be county seat of', Argument/Subject 1: 'bartow', Argument/Subject 2: 'polk county'

Answer: In Bartow , the seat of landlocked Polk County , Howard D. Harley believes he has come up with a more fuel efficient hull design for Florida 's popular flatboats an inverted V shape he says uses up to 40 percent less fuel than others its size .