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Part of the CalcProMaster guides library · Fuel, ownership & running costs
The sticker price is the cheapest part of owning a car. Fuel burn, maintenance, depreciation and the lease-vs-buy decision decide what a vehicle really costs per kilometre — these guides walk the actual math.
Per-kilometre fuel cost is the number every other vehicle decision hangs on: fuel cost per km = fuel price per litre ÷ consumption in km/L. Petrol at $1.50/L with a car doing 12 km/L costs 12.5¢/km — so a 20 km daily commute costs $2.50 each way before parking or tolls.
Compare that with depreciation, which dwarfs fuel on newer cars: a $25,000 car losing 15% of its value in year one costs about $3,000 — roughly $8.20 a day whether you drive or not. That asymmetry is why the lease-vs-buy and EV-comparison guides ask for your annual mileage first: high mileage favors efficient ownership, low mileage questions owning at all.
MPG vs L/100km — the two fuel-economy scales and why they invert.
Dealer “extra 20% off” stacking math before you sign.
Fuel cost per km = price per litre ÷ consumption (km/L), or price × (L/100km) ÷ 100. Add maintenance and insurance divided by your annual kilometres for the true per-km ownership figure.
They are reciprocal scales: higher MPG is better, lower L/100km is better. L/100km = 235.215 ÷ MPG (US). The unit conversion guide keeps the factor handy.
Fuel Cost Calculator Car Loan EMI Calculator EV vs Petrol Cost