EV running costs after RUC: does the Leaf still make sense?

NZTA's new RUC rates for light electric vehicles are now in force. We work through what Leaf and Prius PHEV owners in Canterbury are actually paying per kilometre, and whether used EVs still beat a comparable petrol import on cost.

The RUC exemption for light EVs was always a policy bridge, not a permanent subsidy. NZTA signalled the end of it clearly enough. What was less clear, until you sit down with a calculator, is how much it actually shifts the per-kilometre cost of running a used Leaf or a Prius PHEV once you fold the new rate into everything else.

Let's use a realistic Canterbury commuter as the baseline: 15,000km a year, a mix of city and open road, home charging overnight on a standard tariff around 28 to 32 cents per kWh.

What a Leaf now costs per kilometre

A 2018 Nissan Leaf ZE1 with a 40kWh battery will use somewhere between 16 and 20kWh per 100km in real-world mixed driving. Call it 18kWh as a working figure. At 30 cents per kWh, that's $5.40 per 100km in electricity. Add the new RUC rate of $76 per 1,000km, which works out to $7.60 per 100km, and your combined energy and road-user cost is $13.00 per 100km. Annualised over 15,000km, that's $1,950.

Under the old exemption, that same driver was paying only the electricity cost: $810 a year. The RUC change has added $1,140 to the annual running sheet. That is not trivial on a car that cost $16,000.

There are still savings elsewhere. A Leaf has no cambelt, no exhaust, minimal brake wear from regenerative braking, and servicing is cheaper than a petrol car at a competent EV workshop. Budget $300 to $400 a year for a Leaf service versus $500 to $700 for a petrol Japanese import with a CVT that needs fluid changes. The gap is real but it does not close the RUC gap on its own.

Battery health is the other variable nobody prices correctly. A 2018 ZE1 with 80,000km and 10 to 11 bars of battery capacity is fine. One sitting on 8 bars is not, because usable range drops to somewhere around 180 to 220km and the car's resale case gets harder every year. Always check the battery state of health report before buying. Any dealer unwilling to produce one should be walked away from.

The Prius PHEV picture

The 2017 to 2020 Toyota Prius PHV (the plug-in variant, not the standard hybrid) sits in a different spot. These have been paying reduced RUCs for a while, and the new rate applies to the electric portion of their operation. In practice, most Prius PHEV owners are running the first 50km or so on electricity and then rolling on petrol, which means their actual EV kilometres per year might be 6,000 to 9,000 out of 15,000 total. RUCs apply only to those electric kilometres, not the petrol ones, which are taxed at the pump.

Run that through the numbers: 8,000 electric km at $76 per 1,000km is $608 in RUCs. Add electricity costs for those 8,000km at roughly 13kWh per 100km and 30 cents per kWh, that's $312. Petrol for the remaining 7,000km at the Prius's real-world 4.5L per 100km and $2.70 a litre is about $850. Total annual energy and RUC cost: roughly $1,770.

A standard 2018 Prius doing 15,000km entirely on petrol at 4.8L per 100km and $2.70 a litre spends around $1,944 on fuel alone, with no RUC obligation. The PHEV still wins on annual running costs, but the margin is smaller than it was, and a Prius PHEV is typically $4,000 to $6,000 dearer to buy than a standard Prius at current Canterbury used-car prices.

Does the used EV case still hold?

Against a straight petrol import, the Leaf still saves money over time, but the payback period has lengthened. A 2018 Aqua running 15,000km a year spends around $1,620 on petrol at 4.5L per 100km. That is cheaper than the post-RUC Leaf figure of $1,950. The Aqua also costs $3,000 to $5,000 less to buy in the first place.

The servicing advantage still tilts toward the Leaf, and if you are charging off a solar setup or a cheap overnight rate, the electricity cost per 100km drops enough to change the arithmetic. At 20 cents per kWh, the Leaf's energy cost falls to $3.60 per 100km, and suddenly it is competitive again despite the RUC.

For a Canterbury driver who racks up big kilometres on the open road, the Leaf's 250km real-world range on a healthy battery is a practical constraint in a way it simply is not for an Aqua. Christchurch to Queenstown is around 480km. That requires planning with a Leaf. It does not with a hybrid.

The short version: the used EV argument used to be almost automatic on cost grounds. It is now a proper calculation, not a foregone conclusion. Run your actual kilometres, know your charging rate, check the battery health, and then compare. The Leaf can still win. It just no longer wins by default.