Fuel is where electric wins, and it wins big
A petrol car doing 8 L/100 km at 1.70 per litre costs 13.60 per 100 km. An efficient EV using 16 kWh/100 km on a 0.30 tariff costs 4.80 — roughly a third. Scale that to 15,000 km a year and the gap is around 1,300 a year, before you touch maintenance.
The comparison narrows if you charge exclusively on expensive public DC. At 0.70 per kWh the same EV costs 11.20 per 100 km, close to petrol parity. This is the real reason home or workplace charging matters so much to EV economics — it is not convenience, it is the entire business case.
What this calculator deliberately leaves out
It compares energy, not everything. Insurance, depreciation, tyres, registration and repairs vary far too much by market and model to model meaningfully, and adding invented averages would make the answer look more precise than it is.
Two real-world adjustments worth making yourself: EVs generally cost less in servicing — no oil changes, no timing belts, far less brake wear thanks to regeneration — but they get through tyres faster because of weight and torque. Those two partly cancel, which is why energy cost remains the dominant term.
And the scooter case, which is not close
If the trip you are replacing is a short urban one, a scooter is not competing with a car on cost — it is annihilating it. A 500 Wh scooter covers 25 km for about 17 cents of electricity. The same trip in a petrol car costs 3–4 in fuel alone, plus parking.
Set the EV column to scooter numbers — around 22 Wh/km, so 2.2 kWh/100 km — and the per-100 km cost lands near 0.66. That is the arbitrage micromobility runs on, and it is why so many two-car households quietly became one-car-and-a-scooter households.
Fuel economy conversions
The single most common error in these comparisons is mixing US and imperial gallons. An imperial gallon is 20% larger, so "30 mpg" means two noticeably different things depending on which side of the Atlantic wrote it.
| L/100km | US mpg | Imperial mpg | km/L |
|---|---|---|---|
| 4.0 | 58.8 | 70.6 | 25.0 |
| 5.0 | 47.0 | 56.5 | 20.0 |
| 6.0 | 39.2 | 47.1 | 16.7 |
| 7.0 | 33.6 | 40.4 | 14.3 |
| 8.0 | 29.4 | 35.3 | 12.5 |
| 10.0 | 23.5 | 28.2 | 10.0 |
| 12.0 | 19.6 | 23.5 | 8.3 |
Where electric wins, and where it does not
Home charging is the entire business case. A mid-size EV at 18 kWh/100 km on a 0.30 tariff costs 5.40 per 100 km. The same car on 0.70 public DC costs 12.60 — which is roughly what a petrol car doing 7.5 L/100 km costs at 1.70 a litre. The vehicle did not change; the tariff did.
This calculator deliberately compares energy only. Insurance, depreciation, registration and repairs vary far too much by market and model to average honestly, and inventing figures would make the answer look more precise than it is. Two adjustments worth making yourself: EVs generally cost less in servicing — no oil changes, no exhaust, far less brake wear thanks to regeneration — but they get through tyres faster because of weight and torque. Those partly cancel, which is why energy remains the dominant term.
And if the trip you are replacing is a short urban one, this is not a close contest at all. Set the electric column to scooter numbers — around 2.2 kWh/100 km — and watch what happens to the per-kilometre figure. The charging cost calculator covers that case in more detail.
Questions riders actually ask
How do I convert mpg to L/100km?
For US mpg: L/100km = 235.215 ÷ mpg. For UK (imperial) mpg: L/100km = 282.481 ÷ mpg. So 30 US mpg is 7.84 L/100km, while 30 UK mpg is 9.42 L/100km — a 20% difference that catches people out constantly.
What is the electric equivalent of miles per gallon?
MPGe, which the EPA defines by treating 33.7 kWh as energy-equivalent to one gallon of petrol. An EV using 30 kWh per 100 miles scores about 112 MPGe. It is useful for comparing EVs to each other but tells you nothing about cost, since electricity and petrol are priced completely differently.
Do EVs really need less maintenance?
Materially less on the drivetrain: no oil, filters, spark plugs, exhaust or gearbox service, and brake pads that often last two to three times longer because regeneration does most of the slowing. Tyres, suspension, cabin filters, coolant and wipers are unchanged, and tyres typically wear faster.
How long until an EV pays back its higher purchase price?
Divide the price difference by the annual energy saving. A 6,000 premium against a 1,300 yearly saving pays back in about 4.6 years — sooner with high mileage or expensive fuel, later if you charge publicly or drive very little. The break-even figure here does exactly that arithmetic.
Should I include the cost of installing a home charger?
Yes, as a one-off added to the price difference. A typical wallbox install is 800–1,500 depending on your electrics and any grant available. It usually adds under a year to break-even and immediately halves your charging cost against public rates.