The formula with 32 substituted
km/L = 32 × 0.425144 = 13.60
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The MPG to km/L Converter explains where each comes from and gives a longer table.
The same 32 mpg (US) is 38.43 mpg on the imperial gallon, 7.35 L/100km and 13.60 km/L. If your 32 mpg figure came from a British source it already uses the imperial gallon, and the metric answer is 11.33 km/L instead.
What 32 mpg (US) means in practice
32 mpg (US) converts to 13.60 km/L, a typical mid-size sedan. A British 32 mpg, on the imperial gallon, is only 11.33 km/L, which shows how much the gallon matters in this conversion.