In the end this sorta works: https://www.wolframalpha.com/input?i=convert+%285+mpg%29+to+%28L%2F%28100+km%29%29 https://www.wolframalpha.com/input?i=convert+%28

In the end this sorta works: https://www.wolframalpha.com/input?i=convert+%285+mpg%29+to+%28L%2F%28100+km%29%29 https://www.wolframalpha.com/input?i=convert+%285+mpg%29+to+... Because way down in the "Corresponding quantities" it shows "0.47 L/km" and "47 L/100 km" :)