Example:
15 mile per US gallon = 6.377156e-9 Tm/L
1 mile per US gallon = 4.251437e-10 Tm/L | 1 Tm/L = 2.352146e+9 mile per US gallon
Conversion Steps:
15 × (425.1437075 / 1e+12) = 6.377156e-9