Answer: Car B.
Explanation:
Produce a Miles/Gallon value for each car by selecting a representative distance travelled. I picked three. Divide the miles by the gallons of fuel consumed. mpg = miles/gallon
Car C: (81/3) = 27 mpg
Car A: (200/8) = 25 mpg
Car B: (140/5) = 28 mpg
Car B wins, by a small margin