Fuel Cost per 100 km

L/100km and cost per 100 km: the European metric

In Europe efficiency shows up as liters per 100 km, where a smaller number is the better one. That flips the logic of km/L. To convert, use L/100km = 100 / (km/L), and the trip cost in the same unit comes from cost_per_100km = (100 · price_per_L) / km_per_L. Take a car doing 12 km/L with fuel at R$ 6.20/L as an example: 100/12 lands around 8.33 L/100km, which works out to R$ 51.67 for every 100 km you drive.

Applications: ICE vs EV cost comparison

Putting different powertrains side by side gets simpler in L/100km. A Tesla Model 3 doing ~15 kWh/100km on electricity at R$ 0.70/kWh runs about R$ 10 per 100 km. Cover the same distance in a gasoline car at 12 km/L and R$ 6/L and you are near R$ 30 per 100 km, around three times as much. The calculation earns its keep when you are weighing a new BEV against an ICE, working out what a fleet will cost, or reading the fuel figures printed on European spec sheets.

FAQ

Why is the European unit inverse to km/L? Fuel use rises in a straight line with L/100km, and so does cost. Each extra unit just means more liters in the tank and more reais out of pocket.

Is 7 L/100km good? It is. That comes to roughly 14.3 km/L, toward the top of what you see from popular gasoline compacts.

How do I include ethanol on a flex car? Plug in the price and the consumption you get on that fuel. Then fall back on the 70% rule, which says ethanol pays off as long as its price stays at or below 70% of gasoline's.

Does it work for electric cars? Swap L for kWh and the price per L for R$/kWh. The formula stays the same and hands you the cost per 100 km.