How does the Wattcalc EV vs petrol calculator work?

It compares the total cost of ownership for an electric vehicle and a petrol car over 5 or 10 years. Year zero is the purchase price; each subsequent year adds annual fuel (electricity for the EV, petrol for the ICE) and annual servicing costs. The break-even year is when the EV's cumulative cost first falls below the petrol car's.

What's a realistic EV efficiency in kWh per 100 km?

Most current Australian-market EVs use 16-22 kWh per 100 km on a real-world drive cycle. Smaller hatches and city cars sit near the bottom of that range; larger SUVs and dual-motor performance EVs near the top. The default of 18 kWh per 100 km is a sensible mid-size estimate.

Should I use the home electricity rate or a public charging rate?

Use whichever reflects your charging mix. If you mostly charge at home, the home electricity rate is right. If you regularly use public DC fast chargers (35-70 c/kWh), blend the two — for example, 80% home at 30 c/kWh and 20% public at 60 c/kWh works out to 36 c/kWh.

Why is petrol servicing higher than EV servicing?

EVs have far fewer moving parts — no oil changes, no spark plugs, no exhaust system, no timing belt. Most Australian EV makers publish capped-price service schedules of $200-400 per year, against $1,000-1,500 per year for a typical petrol car including tyres and consumables.

Does this calculator include depreciation, registration or insurance?

No. This is a fuel-and-servicing comparison, plus the upfront purchase price, because those are the figures most buyers ask about. Registration and CTP are roughly comparable across vehicle types in most Australian states. Depreciation and insurance can vary widely by model and driver — get specific quotes for both vehicles before locking in a decision.

EV vs Petrol Cost Calculator Australia

Compare the 5- or 10-year total cost of ownership for an electric vehicle against an equivalent petrol car in Australia. This calculator factors in purchase price, fuel or electricity, and servicing — and shows the year an EV becomes cheaper overall.

Vehicles and driving

EV purchase price ($AUD) Drive-away price after any incentives.

Petrol vehicle purchase price ($AUD) Drive-away price for an equivalent petrol model.

Annual kilometres Australian average is ~13–15,000 km per year.

Comparison period

5 years 10 years

Petrol price (c/L) Recent national average; check FuelCheck/MotorMouth for your area.

Petrol fuel efficiency (L/100km) Combined-cycle figure for the petrol model.

Home electricity rate (c/kWh) Use a charging-time rate if you're on a TOU plan.

EV efficiency (kWh/100km) Typical real-world range for current EVs is 16–22 kWh/100km.

EV annual servicing ($AUD) Most EV makers publish $200–400/yr capped-price schedules.

Petrol annual servicing ($AUD) Includes service intervals, tyres and consumables.

Total cost of ownership

Break-even year

—

when EV becomes cheaper overall

Saving (period)

—

EV vs petrol over selected period

EV total

—

purchase + fuel + service

Petrol total

—

purchase + fuel + service

Electric vehicle

Annual fuel (electricity)—

Annual servicing—

Petrol vehicle

Annual fuel (petrol)—

Annual servicing—

EV cumulative cost Petrol cumulative cost

Year-by-year cumulative cost table

Year	EV cumulative	Petrol cumulative	Difference (Petrol − EV)

How to use this calculator

Use drive-away prices for both vehicles, including any state stamp duty concession or EV incentive that applies in your state.
Use the same body type for a fair comparison — small SUV vs small SUV, mid-size sedan vs mid-size sedan.
Set annual kilometres realistically. Higher mileage helps the EV (because each kilometre is cheaper), lower mileage helps the petrol car.
If you'll mostly charge on a time-of-use tariff overnight, use that off-peak rate (often 18–25 c/kWh) rather than your flat retail rate.
For servicing, use each manufacturer's published capped-price schedule averaged across the comparison period.

Key assumptions

Fuel and electricity prices stay constant for the comparison period. Both have moved over time — adjust the inputs upward if you expect that to continue.
Servicing costs are flat per year, ignoring big-ticket items like timing belts (petrol) or battery service (EV) that may fall in or outside the period.
No depreciation, registration, CTP or insurance — these are usually broadly comparable, but always quote both vehicles for your specific situation.
No fast-charging premium unless you build it into the home electricity rate.
Annual kilometres are constant year on year.

Frequently asked questions

What petrol price should I use?

The most recent national unleaded average from the Australian Institute of Petroleum is a fair starting point. For a personalised view, check FuelCheck (NSW), MotorMouth or your state's fuel-price portal for your local average over the last month.

What EV efficiency is realistic?

Most Australian-market EVs sit between 16 and 22 kWh per 100 km in real-world driving — small hatches at the lower end, large SUVs at the upper. The 18 kWh/100km default works well for a mid-size sedan or small SUV.

Does the calculator include the EV's "free home solar" advantage?

Not directly. If you charge entirely from your own rooftop solar export, your effective electricity rate is closer to the feed-in tariff you would otherwise have earned (typically 4–7 c/kWh). Set the home electricity rate to that figure to model that scenario.

What about depreciation and resale value?

EV residual values in Australia have stabilised but vary widely by brand. If you trust a specific resale forecast, subtract it from each vehicle's purchase price and re-run the calculator with those net costs.

Can I model a hybrid or PHEV?

Sort of. For a hybrid, lower the L/100km figure to the published combined-cycle number — they're not as cheap to run as an EV, but cheaper than a straight petrol car. For a plug-in hybrid, the maths is more complex because it depends on how much of your driving is on electric power; this calculator isn't designed for that.

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