L/100 km = 100 ÷ (km/L) km/L = US mpg × 0.425144 = UK mpg × 0.354006
Worked example
15 km/L = 100 ÷ 15 = 6.67 L/100 km = 15 ÷ 0.425144 = 35.3 US mpg = 15 ÷ 0.354006 = 42.4 UK mpg.
From the Knowledge Base
Worked example 1 — km/L to L/100km. A car covers 18 km/L. Convert to L/100km.
L/100km = 100 ÷ 18 = 5.5555… ≈ 5.56 L/100km.
Check by working backwards: 5.56 L/100km means 5.56 L takes you 100 km, so 1 L takes you 100 ÷ 5.56 = 17.99 ≈ 18 km/L. Matches.
Worked example 2 — US mpg to km/L. A car is rated 32 mpg (US). Convert to km/L.
km/L = 32 × 0.425144 = 13.60 km/L (rounded to 2 d.p.).
Cross-check from first principles: 32 miles = 32 × 1.609344 = 51.499 km. 1 US gallon = 3.785412 L. So km/L = 51.499 ÷ 3.785412 = 13.605 km/L. Matches within rounding.
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