Direct answer
Why MPG and L/100km Move in Opposite Directions
MPG measures distance per fuel; L/100km measures fuel per distance, so better efficiency means higher MPG but lower L/100km.
Question
Why is MPG different from L/100km?
MPG and L/100km are reciprocal measures: higher MPG is better, while lower L/100km is better.
US formula
L/100km = 235.215 / MPG
30 MPG US
7.84 L/100km
Better efficiency
Higher MPG, lower L/100km
Explanation
MPG means miles per gallon, so it measures distance per unit of fuel.
L/100km means liters per 100 kilometers, so it measures fuel consumed over a fixed distance.
For US MPG, L/100km = 235.215 / MPG.