While modern cars have fuel economy gauges built into the trip computers, we haven't yet come far enough to enable them to calculate cost per km in real time. Never say never, though. With ever-fluctuating petrol prices and a need to stay on budget, it's a good practice to calculate your car's cost per km to estimate more precise fuel costs. This is also great for planning your journeys accordingly, particularly for road trips. With this in mind, how do you go about the calculation? Get your calculator out, but fear not, it's not as complicated as it seems.
Calculation Method
In text form, you take the distance travelled, divide it by 100 (that's the typical mileage used in calculations), then multiply the result by the fuel consumption (in l/100km) and the fuel price, to give you the total cost of fuel for the journey. To check the cost per kilometre, divide the fuel cost for the journey by the distance travelled.
Let's use an example: Johannesburg to Pretoria to and fro, with a travel distance of around 100km. We'll use a car like our long-term Volkswagen Golf, which is in good condition and has been for its first service. A good barometer. We achieved the best real-world fuel consumption figure of 6.5 L/100km in that car. Ideally, it's better to use real-world consumption, as the manufacturer's claims are made under perfect conditions during testing, whilst real-world scenarios are not ideal. At the time of typing this, petrol costs R20.10 per litre for 95 octane. We are inland, which affects petrol prices.
100 / 100 = 1 : Distance divided by 100
1 x 6.5 = 6.5: The Above equation's result multiplied by the fuel economy
6.5 x 20.10 = R130.65: Fuel economy multiplied by the fuel price will give the total fuel spent for the journey
To now get the cost per kilometre
130.65 / 100 = R1.30: The total cost of fuel divided by the distance will give you the cost per kilometre
Also, don't forget, a heavy foot equals heavy fines!
