Why cost per 100 km matters
When you are comparing cars, the sticker price is only part of the story. The real question for many drivers is simple: how much does 100 km of driving cost? That number is easy to compare across petrol, diesel, and electric cars, and it helps you estimate your monthly running costs more realistically.
This is especially useful if you are a cost-conscious driver and want a quick way to compare everyday expenses. A car that looks affordable on paper can become expensive if it consumes more fuel, uses pricier energy, or charges inefficiently. On the other hand, a slightly more expensive car may be cheaper to run over time.
For a fast comparison, you can also use an auto consumption calculator, an electric car charging cost calculator, or a broader car ownership cost calculator.
Note: The examples below are for general guidance only. Real costs vary by driving style, route, weather, vehicle condition, and local energy prices.
Formula for fuel cars
For petrol and diesel cars, the basic formula is straightforward:
Cost per 100 km = (fuel consumption in litres per 100 km × fuel price per litre)
If your car uses 6.5 litres per 100 km and fuel costs 650 HUF per litre, then:
6.5 × 650 = 4,225 HUF per 100 km
This formula works for both petrol and diesel. The only difference is the fuel price and the car’s real-world consumption. Diesel cars often use less fuel on the same route, but that does not automatically make them cheaper overall.
Quick example with petrol
Let’s say a petrol car consumes 7.2 l/100 km and petrol costs 640 HUF/litre.
7.2 × 640 = 4,608 HUF per 100 km
If you drive 1,500 km per month, that would be roughly 69,120 HUF in fuel costs.
Quick example with diesel
Now take a diesel car that consumes 5.4 l/100 km, with diesel at 670 HUF/litre.
5.4 × 670 = 3,618 HUF per 100 km
At the same 1,500 km per month, the estimated fuel cost would be 54,270 HUF.
Formula for EVs including charging loss
With electric cars, it is important to account for charging losses. The electricity you draw from the wall is usually higher than the energy that ends up in the battery. That means the cost per 100 km is not just battery consumption multiplied by the electricity price.
A more realistic formula is:
Cost per 100 km = (energy use in kWh per 100 km ÷ charging efficiency) × electricity price per kWh
If your EV uses 17 kWh per 100 km and charging efficiency is 90%, then the wall-side energy is:
17 ÷ 0.90 = 18.9 kWh per 100 km
If electricity costs 70 HUF/kWh, then:
18.9 × 70 = 1,323 HUF per 100 km
That is the key reason why an electric car charging cost estimate should include losses. Home charging is usually cheaper than public fast charging, but the exact result depends on your tariff, charging location, and efficiency.
EV example with public charging
Suppose an EV uses 16 kWh/100 km, but you rely partly on public charging at 110 HUF/kWh. With 92% charging efficiency:
16 ÷ 0.92 = 17.39 kWh
17.39 × 110 = 1,913 HUF per 100 km
That is still often lower than petrol or diesel, but the gap can shrink quickly if you charge mostly away from home.
Example calculations
To make the comparison clearer, here is a simple real-world style snapshot using rounded numbers. These are not official averages, just practical examples you can adapt to your own car and prices.
- Petrol: 7.0 l/100 km × 640 HUF = 4,480 HUF per 100 km
- Diesel: 5.3 l/100 km × 670 HUF = 3,551 HUF per 100 km
- EV: 18 kWh/100 km ÷ 0.90 × 70 HUF = 1,400 HUF per 100 km
In this example, the EV is clearly the cheapest to run per 100 km, followed by diesel, then petrol. But the ranking can change if energy prices move, if you charge mostly at public stations, or if your EV is less efficient in winter.
Here is another scenario that shows how sensitive the numbers are:
- Petrol: 6.0 l/100 km at 680 HUF/l = 4,080 HUF
- Diesel: 5.0 l/100 km at 690 HUF/l = 3,450 HUF
- EV home charging: 16 kWh/100 km at 65 HUF/kWh, 90% efficiency = 1,156 HUF
- EV public charging: 16 kWh/100 km at 120 HUF/kWh, 90% efficiency = 2,133 HUF
The same electric car can look very cheap at home and much less impressive on public chargers. That is why it is worth calculating your own numbers instead of relying on generic averages.
When EVs are not automatically cheaper
Electric cars often have lower energy costs, but they are not automatically the cheapest choice in every situation. Several factors can reduce the advantage:
- Public charging dependence: Fast chargers can cost significantly more than home electricity.
- Charging losses: Inefficiency means you pay for more electricity than the car actually uses on the road.
- Winter consumption: Heating, cold batteries, and winter tires can increase kWh use.
- Higher purchase price: Even if running costs are lower, the total cost of ownership may still be higher depending on financing and depreciation.
- Driving pattern: Frequent motorway trips, towing, or high annual mileage can change the comparison.
For that reason, the cheapest car to drive is not always the cheapest car to own. If you want a fuller picture, combine per-100-km running costs with insurance, servicing, depreciation, and financing. That is where a broader ownership calculator becomes useful.
Also keep in mind that petrol and diesel prices can change quickly, while electricity tariffs may vary by time of day or charging provider. If you want a result that matches your own situation, use your actual HUF/litre and HUF/kWh values rather than a national average.
Try the calculator
If you want to find out mennyibe kerül 100 km autózás for your own car, the fastest way is to enter your real consumption and local prices into a calculator. That gives you a personalized estimate for petrol, diesel, or EV charging in seconds.
Try the fuel cost calculator to calculate your cost per 100 km, then compare it with the EV charging calculator if you are considering an electric car. If you want to look beyond fuel and electricity, the ownership cost calculator can help you estimate the bigger picture.
Ready to compare your own numbers? Open the calculator, enter your HUF per litre or HUF per kWh, and see what 100 km really costs for your car.