Comparing Petrol, Diesel and EV Car Running Costs for 100 KM in 2026
The debate between petrol, diesel, and electric vehicles has become more relevant than ever in 2026. With global fuel prices reaching historic highs due to geopolitical tensions and supply chain disruptions, buyers are carefully evaluating running costs before making a purchase decision. This article provides a detailed, percentage-based comparison of what it actually costs to drive 100 kilometres with each powertrain type in the current market. Understanding these costs helps consumers make informed decisions based on their driving patterns, budget, and environmental priorities.
The Energy Price Landscape of 2026
The first half of 2026 has seen unprecedented volatility in fuel prices across global markets. The conflict in the Middle East triggered a sharp increase in global oil prices, pushing petrol and diesel to record levels across multiple countries including Germany, the United Kingdom, and many other nations. Electricity prices, by contrast, have remained relatively stable during the same period. While wholesale electricity prices are influenced by global gas markets, the availability of renewable energy sources and the ability to charge during low-demand periods have helped maintain more predictable costs for EV owners. This divergence in pricing has created the widest gap yet between the running costs of EVs and internal combustion engine vehicles.
Home Charging Scenario
When EV owners charge at home, the cost advantage over petrol and diesel is substantial. Analysis of customer data from the first quarter of 2026 shows that electric car drivers with smart charging capabilities paid approximately 59 percent less than petrol car drivers and 52 percent less than diesel car drivers. In March 2026, when fuel prices reached their peak, EV drivers with automatic overnight charging saved up to 65 percent compared to petrol vehicles. The gap becomes even more pronounced when EV owners use off-peak electricity tariffs, which can be significantly lower than standard rates. At 100 kilometres, EV running costs are roughly 70 to 85 percent lower than petrol or diesel vehicles when home charging with off-peak rates. This represents the maximum savings potential for EV owners who have access to home charging and smart tariff plans.
Public Charging Scenario
Public charging tells a different story and reduces the cost advantage significantly. The cost of charging at public stations is considerably higher than home charging, with AC chargers having moderate rates and rapid DC chargers being much more expensive. At these higher rates, the cost per mile for public charging can match or exceed petrol costs depending on the charger type used. Home charging remains the primary driver of EV cost savings, and for drivers who rely exclusively on public rapid chargers, the running cost advantage over petrol and diesel narrows considerably or disappears entirely. However, even with mixed public and home charging, EV running costs remain broadly competitive with petrol and diesel vehicles for most drivers who charge primarily at home.
Running Cost Comparison by Vehicle Segment
The running cost advantage of EVs is not uniform across all vehicle types and segments. Smaller vehicles like hatchbacks show a different cost dynamic compared to larger vehicles like SUVs and luxury cars. Understanding these segment-specific differences helps buyers choose the right vehicle based on their needs and budget. The following sections break down the percentage-based cost differences for each major vehicle segment.
Hatchback Segment Comparison
In the hatchback segment, the efficiency difference between petrol and electric is less dramatic than in other segments. Petrol hatchbacks already achieve good fuel economy due to their lighter weight and smaller engines. An electric hatchback is approximately 60 to 70 percent cheaper to run than a petrol hatchback when charged at home. A diesel hatchback is typically 20 to 25 percent cheaper to run than a petrol hatchback but is still about 55 to 60 percent more expensive to run than an electric hatchback. The running cost gap in this segment is smaller than in larger segments because petrol hatchbacks are already relatively efficient.
SUV Segment Comparison
The SUV segment shows the most dramatic cost differences between powertrains. Petrol SUVs are notoriously fuel-hungry due to their weight and poor aerodynamics. Diesel SUVs perform somewhat better but still consume significantly more fuel than smaller vehicles. An electric SUV is typically 70 to 80 percent cheaper to run than a petrol SUV of similar size. A diesel SUV is approximately 25 to 30 percent cheaper to run than a petrol SUV but still costs roughly 50 to 60 percent more to run than an electric SUV. This makes the electric SUV the most compelling choice for buyers in this segment from a running cost perspective.
Luxury and Performance Segment
Luxury and performance vehicles show the widest cost gaps between powertrains. High-performance petrol and diesel engines consume fuel at rates that are substantially higher than standard vehicles. Electric performance vehicles, by contrast, use their energy more efficiently while delivering instant torque and smooth acceleration. An electric luxury or performance vehicle is approximately 75 to 85 percent cheaper to run than a petrol equivalent. Diesel performance vehicles are about 30 to 35 percent cheaper to run than petrol but still about 65 to 70 percent more expensive than electric. For buyers in this segment, the running cost savings of electric vehicles are most compelling.
Driving Conditions and Their Impact
The cost advantage of EVs varies significantly based on driving conditions. Different driving environments affect petrol, diesel, and electric vehicles in different ways. Understanding these differences helps buyers estimate their actual running costs based on their typical driving patterns. City driving and highway driving present very different cost dynamics for each powertrain.
City Driving Conditions
In city driving with frequent stops and starts, EVs show their greatest advantage over petrol and diesel vehicles. Petrol and diesel vehicles are least efficient in city traffic, with fuel consumption increasing substantially compared to highway driving. The constant braking and acceleration in city traffic reduces the efficiency of internal combustion engines significantly. EVs, by contrast, perform very well in city conditions because regenerative braking recovers energy during deceleration and electric motors are most efficient at lower speeds. This means the cost gap between EVs and fossil fuel vehicles in city driving is even wider than on highways, with EVs being approximately 75 to 85 percent cheaper to run in pure city driving conditions.
Highway Driving Conditions
For highway driving, the cost advantage of EVs narrows slightly but remains substantial. At higher speeds, aerodynamic drag becomes more significant and reduces EV efficiency compared to city driving. However, even on highways, EVs remain considerably cheaper to run than petrol or diesel vehicles. The gap is typically 50 to 65 percent in favour of EVs depending on the specific vehicle, driving speed, and charging method used. Diesel vehicles maintain a slight cost advantage over petrol on highways because diesel engines are more efficient at steady speeds, but both remain far more expensive than electric vehicles.
Mixed Driving Conditions
For drivers who do a mix of city and highway driving, the overall cost advantage of EVs falls between the city and highway figures. The typical mixed driving scenario shows EVs being approximately 65 to 75 percent cheaper to run than petrol and 50 to 60 percent cheaper than diesel. This mixed scenario represents the reality for most drivers and demonstrates that EVs remain substantially cheaper to run regardless of driving patterns.
Charging Efficiency Losses
The efficiency of the charging process itself affects the overall running cost calculation. Not all the electricity drawn from the grid reaches the battery because some energy is lost as heat during the charging process. Home charging systems typically have efficiency losses of 5 to 15 percent, meaning the actual cost per kilometre is slightly higher than the theoretical calculation based on battery capacity. Public charging stations may have different efficiency levels, with rapid chargers generally being less efficient than slower chargers.
These efficiency losses reduce the net cost advantage of EVs slightly but do not eliminate it. The 5 to 15 percent loss means that EV running costs are slightly higher than the ideal calculation, but even with these losses, EVs remain at least 50 to 75 percent cheaper to run than petrol and diesel vehicles in most scenarios. Buyers should factor in these efficiency losses when estimating their actual running costs.
Battery Degradation Over Time
Battery degradation over the life of the vehicle affects running costs in the long term. As an EV battery ages, its capacity decreases, potentially reducing the vehicle’s range and increasing the cost per kilometre. The rate of degradation depends on charging habits, climate, and driving patterns. Studies show that battery degradation is relatively slow, with most EV batteries retaining 70 to 80 percent of their capacity after approximately 160,000 kilometres.
This degradation means that the running cost advantage of EVs may decrease slightly as the vehicle ages. However, even with 20 to 30 percent capacity loss, the cost per kilometre of an EV remains substantially lower than petrol and diesel vehicles. The long-term running cost advantage of EVs remains compelling even when accounting for battery degradation over the vehicle’s lifetime.
Seasonal Variations in Running Costs
Seasonal variations affect the running costs of all vehicles but impact EVs differently than petrol and diesel vehicles. Cold weather reduces the efficiency of EV batteries and increases the energy consumption for cabin heating, which can increase running costs by 20 to 40 percent in winter conditions. Hot weather can also affect battery efficiency, though the impact is generally less severe than cold weather.
Petrol and diesel vehicles are also affected by seasonal variations, with winter fuel blends and cold starting reducing efficiency by approximately 10 to 20 percent. The seasonal impact is generally less severe for petrol and diesel than for EVs, meaning the running cost advantage of EVs narrows in winter but remains significant. In summer conditions, EVs perform closer to their optimal efficiency, and the cost advantage over petrol and diesel is maximized.
Regional Variations in Energy Costs
Energy costs vary significantly across different regions and countries, affecting the relative running cost advantage of EVs. In regions with low electricity costs and high petrol prices, the advantage of EVs is maximized. In regions where electricity is expensive and petrol is relatively cheap, the advantage narrows. The growing adoption of renewable energy sources in many countries is helping to keep electricity costs stable while oil prices remain volatile.
The availability of off-peak electricity tariffs also varies by region, with some countries offering substantial discounts for overnight charging. In regions where these tariffs are available, the EV running cost advantage is significantly larger than in regions where they are not. Buyers should research the energy costs in their specific location to accurately estimate the running cost advantage of EVs.
Maintenance Cost Differences
While this article focuses primarily on running costs, maintenance costs are another critical factor in total ownership costs. EVs have fewer moving parts than petrol and diesel vehicles, with no oil changes, timing belts, exhaust systems, or complex transmission components to maintain. This results in significantly lower maintenance costs over the life of the vehicle.
Studies show that EV maintenance costs are approximately 40 to 50 percent lower than petrol vehicles and 30 to 40 percent lower than diesel vehicles over the typical ownership period. This further increases the total cost advantage of EVs when combined with the running cost savings.
Total Cost of Ownership Perspective
When considering the total cost of ownership, the running cost advantage of EVs is just one factor among many. Purchase price, depreciation, insurance, maintenance, and running costs all contribute to the total cost. In 2026, the purchase price gap between EVs and petrol vehicles has narrowed substantially, with many EV models now reaching price parity with equivalent petrol models.
Depreciation patterns also differ between powertrains. Some analyses suggest that EVs may depreciate faster than petrol vehicles due to concerns about battery replacement costs. However, as battery technology improves and warranties extend, this depreciation gap is narrowing. When all factors are considered, the total cost of ownership of EVs is now competitive with or better than petrol and diesel vehicles in many markets.
Future Outlook for Running Costs
The running cost gap between EVs and petrol and diesel vehicles is expected to widen further in the coming years. Oil prices are projected to remain volatile due to geopolitical uncertainties and supply constraints. Electricity prices, by contrast, are expected to become more stable as renewable energy sources expand. Battery technology continues to improve, with new chemistries promising higher efficiency and longer life.
The expansion of charging infrastructure and the growing availability of smart charging tariffs will further enhance the cost advantage of EVs. In the coming years, the running cost advantage of EVs is expected to reach 70 to 80 percent compared to petrol and 60 to 70 percent compared to diesel in most markets.
Conclusion
The running cost comparison for 100 kilometres clearly shows that electric vehicles have a substantial advantage over petrol and diesel vehicles in 2026. When charged at home, EVs are approximately 60 to 85 percent cheaper to run than petrol vehicles and 50 to 75 percent cheaper than diesel vehicles, depending on charging method and driving conditions. Public charging reduces this advantage but still leaves EVs broadly competitive.
The cost advantage is most significant in city driving conditions and for larger vehicles like SUVs where petrol and diesel consumption is highest. Driving conditions, charging methods, and regional energy costs all affect the exact percentage difference, but the overall trend is clear and consistent across markets. EV owners save substantially on every 100 kilometres driven.
Beyond running costs, EVs offer additional advantages including lower maintenance costs, reduced environmental impact, and superior driving characteristics. As battery technology continues to improve and charging infrastructure expands, the cost advantage of EVs is expected to grow further. For most buyers in 2026, choosing an EV represents the most cost-effective option for their daily driving needs.