The short answer is: no, magnets do not increase miles per gallon.
Some gasoline blends or other fuels have molecules with some small degree of polarity, but the use of magnets has no meaningful effect on any flowing fuel in a line, stored in a vessel, or igniting in a cylinder. Magnetic fields cannot make a fuel chemically, hydrodynamically, or thermodynamically any more efficient in any real world use. The only possible place where magnets could possibly improve fuel economy would be as a ferrous-metal trapping filter. (However, if you have ferrous objects in your fuel supply, you already have problems far beyond any corrective filtration.)
34 miles per gallon = 54.72 kilometers per gallon.
Between 13 miles per gallon and 16 miles per gallon.
14 to 15 miles per gallon city driving---3.78 litres per gallon, 20-21 miles per gallon highway. 14 to 15 miles per gallon city driving---3.78 litres per gallon, 20-21 miles per gallon highway.
29.04 miles per US gallon or 34.87 miles per Imperial gallon.
Miles Per Gallon Miles Per Gallon
16.5 miles per gallon
52.27 miles per gallon
MPG = Miles Per Gallon
24.46 miles per gallon.
34.59 miles per gallon.
36.19 miles per gallon.
(700 miles) x (3 bux per gallon) / (14 miles per gallon) = 150 bux