EV running costs after 2027: what the RUC exemption end actually means

The government's RUC exemption for light EVs expires 31 March 2027 with no confirmed extension. Here's what that does to the per-kilometre numbers for a used Leaf or Atto 3.

The RUC exemption for light EVs ends on 31 March 2027. No extension has been confirmed. If you are buying a used EV right now, that deadline is roughly 27 months away, which is well within the ownership window of a car you might drive for five or six years.

The question is straightforward: once RUCs land, does a used Nissan Leaf or BYD Atto 3 still beat a comparable petrol or diesel import on running costs? The answer depends on how far you drive, what you pay for power, and which petrol car you are comparing against. The numbers are worth doing properly.

What RUCs actually cost per kilometre

The post-exemption RUC rate for light EVs is $76 per 1,000km, the same as the equivalent road-funding contribution already baked into petrol through fuel excise. At 15,000km per year, that is $1,140 annually, or about $95 a month. At 20,000km, it is $1,520. Those are not catastrophic numbers, but they are real money that does not appear in any current EV ownership cost estimate you will find online.

By comparison, a petrol driver pays fuel excise embedded in the pump price. At current petrol prices around $2.50 to $2.80 per litre, a car doing 7L/100km over 15,000km burns through roughly 1,050 litres a year. At $2.65 average, that is about $2,783 in petrol. A comparable diesel at 6L/100km costs less per litre but attracts RUCs already, currently $74 per 1,000km for light vehicles, so diesel drivers are already living with the system EVs are about to enter.

Running the numbers: Leaf versus Corolla

Take a realistic used-market comparison. A 2018 Nissan Leaf 40kWh, compliance-plated and on the road, sits around $18,000 to $22,000 in the current Canterbury market. A 2018 Toyota Corolla hatch in similar condition runs $17,000 to $21,000. Close enough to treat as equivalent purchase price.

The Leaf's electricity cost at home charging, assuming roughly 18kWh per 100km real-world and a blended rate of 28 cents per kWh, works out to about $5.04 per 100km. Add post-2027 RUCs of 7.6 cents per km and you are at $12.64 per 100km. The Corolla at 7L/100km and $2.65 petrol is $18.55 per 100km. The Leaf still wins by about $6 per 100km, or $900 a year at 15,000km.

That gap is real, but it is about half what EV enthusiasts typically quote today, when RUCs are zero. Before March 2027, that same Leaf costs around $5 per 100km all-in on electricity. Post-RUC, it is $12.64. The Corolla does not change. The Leaf's annual fuel-and-road-cost advantage drops from roughly $2,030 to around $880.

Where the BYD Atto 3 sits

The Atto 3 is a newer, heavier car. Used 2022-23 examples are coming in around $34,000 to $40,000, which puts it up against a 2020-21 Mazda CX-5 petrol at similar money. The Atto 3 draws more power, around 20 to 22kWh per 100km in real-world Canterbury use with heaters running. At 28 cents per kWh that is $5.60 to $6.16 per 100km electricity. Post-RUC, add 7.6 cents, and you are looking at $13.20 to $13.76 per 100km.

A CX-5 2.0-litre petrol does around 8L/100km in mixed driving. At $2.65, that is $21.20 per 100km. The Atto 3 still saves roughly $7 to $8 per 100km, which at 15,000km a year is $1,050 to $1,200. Not nothing, but across a five-year ownership the total fuel saving might be $5,500 to $6,000, which only partially offsets a purchase price premium that can easily be $8,000 to $10,000 over the equivalent petrol CX-5.

Servicing costs complicate the picture in the Atto 3's favour. Fewer oil changes, no timing chain, no exhaust system. Against that, battery health on a used Atto 3 is still an unknown at higher mileage, and BYD's parts and service network in New Zealand is thin outside the main centres.

What buyers should actually do

If you are high-mileage, say 20,000km or more per year, the EV case holds up even after RUCs, though it weakens. If you are doing 10,000km a year, the running cost advantage largely disappears once you account for $760 in annual RUCs on top of electricity. At that point the decision comes down to the car itself, not the fuel savings.

The 2027 deadline also creates a practical window. Buyers who purchase an EV now get roughly two more years of RUC-free driving before the levy lands. On 15,000km per year, that is $2,280 in RUCs they will not pay. That is worth factoring into the purchase negotiation today, because it is a genuine time-limited benefit that will not be available to someone buying the same car in mid-2027.

What nobody can tell you is whether the government extends the exemption. There has been no signal either way. Budgeting as though the exemption ends on schedule is the only honest approach.