EV charging cost vs petrol running costs

Comparing the two cost models

The cost of fuelling a vehicle is one of the largest variable costs of ownership, and the difference between electric and internal-combustion economics is one of the most-debated questions in modern car buying. The honest answer is: it depends, and the variables are easy to model once isolated.

Per-kilometre fuel cost depends on three inputs for an internal-combustion vehicle:

• The fuel price (per litre)
• The fuel consumption (litres per 100 km)
• The driving distance

For an electric vehicle, the inputs are:

• The electricity price (per kWh)
• The energy consumption (kWh per 100 km)
• The driving distance
• A charging efficiency factor — energy drawn from the wall versus energy stored in the battery

The two formulas produce a per-kilometre cost figure that can be compared directly.

Internal-combustion vehicle running cost

The formula:

Cost per km = (Fuel price × Consumption) ÷ 100

For a vehicle consuming 7.5 L/100 km at a fuel price of $1.80 per litre:

Cost per km = ($1.80 × 7.5) ÷ 100 = $0.135 per kilometre, or roughly $13.50 per 100 km.

Across an annual driving distance of 15,000 km, that is $2,025 in fuel cost per year.

Real-world consumption usually exceeds manufacturer claims. Standard test cycles produce optimistic figures because they are run under controlled conditions with smooth driving, no air conditioning, and low load. Real-world consumption typically runs 10–25% above the published figure, depending on driving pattern, terrain, and load.

A pragmatic approach is to track actual fuel consumption over several months from receipts and odometer readings, rather than rely on the marketing number. The difference for a typical vehicle is $300–600 per year in fuel cost between optimistic and realistic assumptions.

Electric vehicle running cost

The formula:

Cost per km = (Electricity price × Consumption × Efficiency factor) ÷ 100

For a vehicle consuming 18 kWh/100 km charged at $0.30 per kWh with a 90% charging efficiency factor:

Cost per km = ($0.30 × 18 ÷ 0.90) ÷ 100 = $0.060 per kilometre, or $6.00 per 100 km.

Across 15,000 km annually, that is $900 in electricity cost — roughly half the petrol cost in the example above.

The efficiency factor matters. Energy drawn from a wall socket exceeds energy stored in the battery because some is lost as heat in the charging process. For most home AC charging, the loss is 8–12%. For DC fast charging, losses are typically smaller for the charge itself but the per-kWh price is much higher, often making the all-in cost worse despite the efficiency.

Home charging vs public charging

The single largest variable in EV running cost is where the vehicle is charged.

Home charging at off-peak rates is typically the lowest cost. Many electricity markets offer overnight or controlled-load tariffs at $0.10–0.20 per kWh, producing per-kilometre costs of $0.02–0.04. A driver who charges 90%+ at home benefits from these rates across most of their driving.

Home charging at standard rates is mid-range. Rates of $0.25–0.40 per kWh produce per-kilometre costs of $0.05–0.08, comparable to or slightly cheaper than petrol depending on the local fuel price.

Public AC charging typically runs $0.40–0.60 per kWh, producing per-kilometre costs of $0.08–0.12 — comparable to petrol or higher in some markets.

DC fast charging is the most expensive option, often $0.60–0.90 per kWh, producing per-kilometre costs of $0.12–0.18 — frequently more expensive per kilometre than petrol despite the EV’s mechanical efficiency advantage.

A driver who charges only at fast chargers can spend more per kilometre than a similar petrol vehicle. A driver who charges at home off-peak can spend a fraction of the petrol cost. The same vehicle in two different driver hands produces dramatically different running cost outcomes.

Electricity rate variability

Electricity tariffs vary by region, time of day, and contract structure. The typical patterns:

• Time-of-use tariffs charge higher rates during peak periods and lower rates overnight. EV owners with a charger at home benefit by scheduling charging into the off-peak window.
• Controlled-load tariffs dedicate a separate meter to a specific appliance (often the EV charger or hot water system) at a heavily discounted rate, on the basis that the utility can throttle it during demand spikes.
• Solar self-consumption changes the math. A household with rooftop solar generating during the day and an EV charging at home effectively pays close to zero per kilometre for charging, after the fixed cost of the solar system is amortised.

The implication is that EV running cost is more controllable than petrol cost. Petrol drivers are largely price-takers; EV drivers can shift consumption into cheap periods or generate their own electricity.

Maintenance cost differences

Running cost is the most-discussed gap between EV and ICE, but maintenance cost is often more material across a long ownership period.

Internal-combustion vehicles incur regular costs for:

• Engine oil and filter changes (typically every 10,000–15,000 km)
• Spark plugs, fuel filters, and air filters
• Cooling system service
• Transmission service
• Exhaust system repairs
• Belts, hoses, and gaskets that age and require replacement

Most of these costs are absent or substantially reduced for electric vehicles. EVs do still require:

• Tyre replacement (typically faster than ICE because EVs are heavier and accelerate harder)
• Brake fluid and brake-related service (less frequent because of regenerative braking)
• Cabin air filters
• Coolant for battery thermal management systems
• 12V battery replacement

Across a typical five-year ownership, maintenance cost on a comparable EV is often 30–50% lower than on an ICE equivalent. The exact saving depends heavily on the specific vehicles compared and the driver’s service habits.

Total running cost over 5–10 years

A reasonable comparison combines fuel and maintenance over a multi-year horizon. Consider a vehicle driving 15,000 km per year over five years.

Internal-combustion vehicle:

• Fuel cost: $2,025 × 5 years = $10,125
• Maintenance: $700/year × 5 = $3,500
• Total running cost: $13,625

Electric vehicle (mostly home off-peak charging):

• Electricity cost: $400/year × 5 = $2,000
• Maintenance: $400/year × 5 = $2,000
• Total running cost: $4,000

The five-year running cost gap is roughly $9,600 — a meaningful fraction of the typical $5,000–10,000 purchase-price premium an EV currently carries in many markets.

The full picture, however, must include depreciation, insurance, and any registration differential — not just running costs. EVs in some markets depreciate faster than ICE equivalents, partially offsetting the running-cost advantage. Insurance can be higher because of more expensive parts. The complete view requires a total cost of ownership calculator rather than a fuel comparison alone.

How the calculator helps

The HoldingCost EV savings calculator computes the running-cost gap between an electric and an internal-combustion vehicle using configurable assumptions about driving distance, fuel price, electricity price, consumption rates, and charging mix. The fuel cost calculator computes per-kilometre and annual cost for any internal-combustion vehicle from real-world consumption.

Use them together when shopping a new vehicle to model the multi-year running cost difference, when deciding whether to switch from an existing ICE to an EV, and when negotiating which charging tariff and home-charging setup will deliver the best running cost.

Practical takeaways

Per-kilometre cost can favour either powertrain depending on energy prices and charging mix. The biggest single lever is home charging at off-peak rates. Maintenance differences compound over multi-year horizons and meaningfully change the total picture. And finally — neither powertrain is universally cheaper. The right answer depends on the specific vehicles, the driver’s charging access, and the holding period being modelled.

This guide is general information only and does not constitute financial advice. Energy prices, vehicle costs, and depreciation curves vary significantly by market. Confirm assumptions against your local prices and your actual driving pattern before relying on any modelled figure.