Example:
15 Gm/L = 30638786.547166 nautical mile per US gallon
1 Gm/L = 2042585.769811 nautical mile per US gallon | 1 nautical mile per US gallon = 4.895755e-7 Gm/L
Conversion Steps:
15 × (1e+9 / 489.5755247) = 30638786.547165804