Petrol is $3.40 a litre. Here is what charging an EV at home actually costs.

Quick answer: Petrol is averaging around $3.40 a litre, and the AA says it can't see any sign of that falling. On EECA's figures, which use 2024 prices, driving 100km in a petrol car cost about $19, and so did an EV topped up at a public fast charger. Charge the same EV at home, off-peak, and it was about $11. Road user charges are included in all three. Petrol has moved since, so treat those as a guide to the gap rather than today's exact costs. So the saving from an EV is real, but it lives almost entirely in your garage or driveway. If you would mostly be fast-charging, the running cost barely moves.

What is going on with petrol

91 petrol is above $3 a litre right across the country, and averaging roughly $3.40, according to RNZ's reporting on 25 September. Oil has gone back over US$100 a barrel.

The AA's Terry Collins was blunt about where it goes from here: "I do not see any indication that prices would fall." The best case he offered was that the rises "may slow down, they may stabilise."

Nobody can tell you what petrol will cost next year, and it would be odd to buy a car on a guess about oil prices. But it is a fair moment to look at what you are actually paying to drive, and what the alternative costs.

What an EV costs to run

EECA works this out per 100km, with road user charges included, which matters now that EVs pay them. These are its figures at 2024 prices:

• Petrol car: about $19
• EV at a public fast charger: about $19
• EV charged at home, off-peak: about $11

Those figures come from the Electric Homes technical report that EECA and Rewiring Aotearoa published in March 2024. Petrol is now around $3.40 a litre. We have not tried to re-run their sums at today's price, because that would be our arithmetic wearing their name, but the direction is not hard to follow.

The bit people miss: where you charge

Look again at those three numbers. A fast-charged EV costs about the same to run as a petrol car.

That is not a knock on fast chargers. They are brilliant for a road trip, and they are what makes a Wellington to Taupō run easy. But they are priced for convenience, and if most of your driving ran on them you would not save much on running costs at all.

The saving comes from charging at home, off-peak, overnight when power is cheapest. That is where almost all of the difference between $11 and $19 comes from, and it is already how most owners do it: EECA says around 80% of EV owners do more than half of their charging at home.

So the useful question is not really "should I get an EV". It is "can I charge one at home". If you have off-street parking and can get a charger to it, the numbers work well. If you rely on on-street parking with no way to charge, they work much less well, and it is better to know that before you buy than after.

One thing worth knowing about the plug-in charger that comes with most EVs: EECA's advice is that these portable chargers on a standard socket are fine when nothing else is available, but they are not designed to be your main way of charging, and are unlikely to suit longer-range EVs. A wall-mounted charger has to be installed by a registered electrician.

What this does not cover

Running cost is one line in a bigger sum. It leaves out:

• What you pay for the car. A used EV and a new one are very different decisions, with very different price tags. We've looked at whether a second-hand EV is worth it, and at getting one through your employer.
• Insurance and servicing. These vary a lot by model and are worth pricing separately.
• Your own power plan. Off-peak rates vary a lot between retailers, and some plans are built specifically for EV charging.
• How far you drive. The more kilometres you do, the more the per-100km difference adds up.

Frequently asked questions

How much does it cost to charge an EV at home in New Zealand?

About $11 per 100km charged off-peak, on EECA's figures at 2024 prices, with road user charges included.

Is a fast charger cheaper than petrol?

Not really. On EECA's 2024 figures, a public fast charger cost about $19 per 100km, the same as a petrol car.

Do EVs pay road user charges?

Yes. EECA's running-cost figures include them.

Will petrol prices come down?

Nobody knows. The AA said in late September that it did not see any indication prices would fall.

What should I check before buying an EV?

Whether you can charge it at home. That is where most of the running-cost saving comes from.

Run your own numbers

What an EV saves you depends on how far you drive, where you can charge and what your power plan looks like. The Cogo platform works that out for your household and puts you in touch with vetted installers if you want a home charger quoted.

See what an EV would save your household

This article is general information only. It is not financial, energy or product advice. What you save depends on your home, your power plan and how you use energy, so get quotes from qualified installers or licensed dealers and seek independent advice for your own situation.