Whether an EV saves you money depends on where it is at noon.
Most answers use an average driver, an average tariff and an average petrol price. Your fill-ups give your own driving, and your power plan prices the charging, but a cheap midday window only helps if the car is parked at home then. Paste a few fill-ups and see what it comes to. Free, in your browser.
- EV, in the free window
- $0
- EV, either side of it
- about $3.00
- EV, overnight
- about $5.20
- EV, at peak
- about $8.80
- my second car, on petrol
- about $16.30
Free from 12 to 3, if the car is home. My commuting car was home for the whole window on 8 of the 21 days I logged, so in a normal working week more of its charging would land overnight.
the check
your petrol, the EV, your powerper 100 km, fuel only
- petrol
- about $16.30
- EV, on your mix
- about $5.20
About $1,100 a year less on fuel, on 10,000 km.
Each $1,000 an EV costs over the petrol car takes about 9,000 km to earn back.
The post’s figures: my second car against an EV charged overnight.
when it would charge
- cheap window 0%
- overnight 100%
- peak 0%
28.7 kWh a week from the wall. With the car never home for the window, none of it is cheap. Average 35c a kWh.
what moves it
- All at peak: about $8.80 per 100 km, still about $750 a year less than petrol.
- The petrol price: on this mix an EV stops saving below about $0.74 a litre.
- The weather: a hot day with the air-con on, about $6.30 per 100 km; a 0 °C morning, about $6.70. Between 10 and 31 °C, Geotab’s 4,200 EVs lost next to nothing.
- petrol:
- 7.10 L/100 km × $2.30 = $16.33
- EV:
- 14.95 kWh from the wall × 35c = $5.23
- a year:
- $11.10 × 10,000 km ÷ 100 = $1,109.75
Fuel only. Servicing, tyres, insurance, registration and resale are outside these sums.
where to find the numbers
receipts, your bill, a week of noticingYour fill-ups
Receipts, a fuel app or a note in the glovebox: the date, the litres, the dollars and the odometer. Fill to the click each time for a month and the litres line up with the kilometres.
How you drive
An EV's figure depends on speed more than anything. Suburban driving sits near 13 kWh per 100 km in a small EV; a lot of 110 km/h freeway pushes it towards 20.
Your power bill
The price per kWh at each time of day, in cents. Many plans now have a free or cheap window in the middle of the day, and overnight is usually the next best.
Where the car is at noon
Note it for a couple of weeks. A car at work while power is cheap charges at the overnight or peak price instead, and that is most of the difference.
not sure the sums are right?
Send me your figures.
If the answer looks odd, or you’re not sure which price your car would really charge at, email me the fill-ups or the three figures, your power prices and the days the car is home at noon. I’ll tell you what I see, in a sentence or two, usually within a day. Free.
Your figures stay in my inbox. Nothing about them goes on this site, and I don’t keep a list.
free
One email, with the figures in the body or the saved picture attached. No form, no sign-up.
Email my figuresif you want it read properly
one hourthe read · one hour
$90
You send your fill-ups or a few weeks of driving, a recent power bill and your plan. I work out, remotely, which plan, which charger, if any, and which charging times make the sums work for how your car is used, and write it back.
If it needs more than the hour, I say so before, not after. The first 20 minutes on the phone are free.
questions
9 answeredIs anything I type or paste sent anywhere?
No. The fill-ups are read and the sums are done in your browser, and nothing is stored. Like every page on this site, it counts that it was viewed, and nothing else: no cookies, no trackers. If you email me your figures, that is the one thing that reaches me.
Why fill to the click?
Filling until the pump clicks off leaves the tank at the same level each time, so the litres you put in are the litres the car used since the last fill. The page adds up every fill after the first and divides by the kilometres between the first and last. Part fills make that wrong for the stretch they're in; over a month or two it mostly evens out.
Why add 15% for charging?
Some power is lost between the wall and the battery. ADAC, the German motoring club, measured 12.7 to 15.3% of the power lost charging from a normal power point at 2.3 kW, and 5 to 7% from an 11 kW wall charger. So the page adds about 15% for a power point and about 8% for a wall charger. Change it if you know your car's figure.
Where does the kWh per 100 km come from?
EV Database's real-world figures, counted at the battery, for the small EVs sold in Australia: 11 to 13 kWh per 100 km around town in mild weather, 15 to 16 in mixed driving and 18 to 21 at a steady 110 km/h. The page starts at 13, which suits suburban driving. A bigger car, or a lot of freeway, needs a higher figure.
Why does it say nothing about servicing?
Because your fill-ups and power bill can't tell it. Servicing, tyres, insurance, registration and resale value all differ between cars, and an EV can come out ahead or behind on each. The page is fuel only, and says so. Add the rest from quotes for the cars you're looking at.
How does summer or winter change it?
Heat with the air-con on cost five EVs 17% of their range at 35 °C in AAA's test, and cold cost about 22% at 0 °C across Recurrent's data. Less range means more kWh per kilometre, so the page shows the cost per 100 km on those days. Between 10 and 31 °C, Geotab's 4,200 EVs lost next to nothing.
What happens in the one-hour read?
It's one hour at my small-jobs rate, $90, done remotely. You send your fill-ups or a few weeks of driving, a recent power bill and your plan. I work out which plan, which charger, if any, and which charging times make the sums work for how your car is used, and write it back. If it needs more than the hour, I say so before, not after.
Do I need to be in Adelaide?
No. I'm in Adelaide and the read is remote, so it works anywhere in Australia with a bill and some fill-ups. Fitting a wall charger is a job for a licensed electrician near you.
Does the price include GST?
The price shown is the total you pay. Nothing is added on top, and your invoice spells out the GST position.
Price in AUD, last set October 2026. The hour is my small-jobs rate. How I logged two petrol cars to answer this for my own household is in the EV post, and the loggers are on the household stack page.