Recognize the direction of the measure
Miles per gallon measures distance travelled per unit of fuel, so a larger number represents more distance for that fuel. Litres per 100 kilometres measures fuel used for a fixed distance, so a smaller number represents less consumption. The relationship is reciprocal rather than a simple difference in scale. Do not subtract two L/100 km values and expect the same-sized change in mpg across all starting points. First make both figures use the same defined unit.
Distinguish US and imperial gallons
Natural Resources Canada gives different conversion factors: 235.21 divided by L/100 km for US mpg, and 282.48 divided by L/100 km for imperial mpg. Using 8 L/100 km as an illustrative value gives about 29.4 US mpg or 35.3 imperial mpg. Those two mpg results describe the same underlying consumption in different gallon systems. A video that says only mpg needs its original market or explicit unit confirmed before you compare it with another review.
Keep the test category and vehicle version
NR Can distinguishes city, highway and combined ratings, with the combined calculation based on its stated mix. A presenter’s real-world trip, a laboratory rating and an on-screen highway figure can have different conditions. Keep the vehicle’s model year, engine or powertrain and test category with the number. A familiar model name does not guarantee an identical vehicle specification across countries. Correct unit conversion does not remove those other differences.
Make the comparison traceable
Write the original number and unit, the source, the vehicle version and whether it is city, highway, combined or a particular trip. Then add the converted value with sensible rounding. NR Can notes that rounding can affect comparisons of published combined figures, so do not claim a tiny apparent difference proves a meaningful advantage. This is a method for understanding a programme’s measurement, not a purchase recommendation or a prediction of your own fuel use. Retain the original source so another viewer can check the same context.
Related questions
Can35 imperialmpgand29USmpgdescribe similarconsumption?
Yes. The gallon definitions differ; convert with the correct factor.
Does unitconversion make a roadtrip result identical to a combinedrating?
No. Keep the test conditions and vehicle version.
Sources and scope
Scope notes distinguish published documentation, supplied information and editorial methods. They do not report a hands-on service test.
- NR Can fuel-consumptiontables — US/imperialconversionfactors,city/highway/combinedcategoriesandroundingcontext
