You’ve probably heard the line: “EVs pay for themselves in fuel savings.” That was closer to true when the Clean Car Discount was alive and EVs didn’t pay road-user charges (RUC). In 2025, the maths has shifted. NZTA brought EVs into RUC from 1 April 2024, and used EV prices have been wobbly. Sophie in Hamilton learned this the hard way: she bought an EV expecting thousands in savings, then watched RUC bills stack up and dealer trade-in estimates soften. She still loves the quiet drive and low servicing hassle, but the five-year cost wasn’t what she’d pictured. We’ve run the numbers using NZ market prices, MBIE electricity data, NZTA policy, and live dealer pricing to help you avoid that surprise.

BYD Atto 3 and Hyundai Kona parked side-by-side in a suburban driveway
Two common models, side-by-side: the numbers below compare their five‑year costs.

Why do so many buyers get the EV cost maths wrong?

Most people fixate on the petrol vs electricity line. It’s like judging an iceberg by the tip. Fuel/energy is visible and immediate; depreciation and policy are the heavy mass underneath. In 2025, the headline you should start with is “net ownership cost”, not “running cost”. That means purchase price minus resale after five years plus everything you spend to keep it moving (energy/fuel, insurance, maintenance, and - for EVs - RUC).

Here’s the mental pivot. EVs still win on energy and servicing most of the time, but two factors now dominate outcomes: resale value and RUC. If you mostly home charge and your EV holds value, you’re in great shape. If you rely on public fast charging and the model you pick depreciates heavily, the savings evaporate.

Better questions to ask:

  • What will this specific model likely be worth in five years?
  • How much of my charging will be at home vs public? At what tariff?
  • How many kilometres will I actually drive each year?

What does the hard data say in NZ right now?

Let’s pin this to two real models you see on NZ roads: BYD ATTO 3 (standard range) vs Hyundai Kona 2.0 petrol.

  • Purchase prices: BYD ATTO 3 list about $52,990 (BYD Auto NZ). Hyundai Kona 2.0 petrol around $38,990 (current dealer listings).
  • EV energy use: roughly 15 kWh/100 km for the Atto 3 in blended NZ use (owner tests and reviews).
  • Electricity: MBIE’s survey has average retail power around 34-35 c/kWh (May 2024). Public DC fast charging is typically 60-80 c/kWh.
  • Petrol: Kona WLTP consumption about 7.3 L/100 km. Using a representative $2.80/L.
  • Policy: EVs pay RUC at $76 per 1,000 km (NZTA). The Clean Car Discount ended 31 Dec 2023 (NZTA), so no upfront rebate.
  • Insurance and servicing: premiums have trended up across the board (RNZ), with EV insurance often higher for newer, higher-value cars; servicing is generally cheaper on EVs.
Electric vehicle plugged into a home garage charger
Home charging at typical residential rates strongly shifts the ownership maths.

Base-case (15,000 km/year, five years):

  • BYD ATTO 3 running costs per year: about $1,047 for charging (80% home at MBIE’s price, 20% public, with a 10% home-charging loss), $1,800 insurance, $400 servicing, and $1,140 RUC. That’s around $4,387/year.
  • Kona petrol per year: about $3,066 fuel, $1,400 insurance, $900 servicing. Roughly $5,366/year.

The twist: depreciation is the decider. Assume five-year value retention at 40% for the EV and 45% for the petrol (reflecting recent used EV softness). On those settings:

  • ATTO 3 five-year net ownership cost ≈ $53,729.
  • Kona 2.0 five-year net ownership cost ≈ $48,274.
  • Difference ≈ $5,455 more for the EV over five years.

How would the wrong choice feel day to day?

Picture two Mondays. In the Kona, you feel the pinch at the pump - another $90 gone - and a big service due before the summer roadie. In the Atto 3, you glide past the servo, plug in at home overnight on a cheaper rate, and spend very little on servicing. But then it’s rego time and you preload RUC again, and when you think about changing cars, the trade-in offer for your EV stings more than you expected.

Now flip it. If you’ve got a driveway, a smart off-peak power plan (or solar), and you rack up 20,000 km a year, the Atto 3 quietly saves you money every month. Your costs feel boring and predictable. And the pride of cutting tailpipe emissions on the school run and the commute? Hard to put a price on that.

What’s the smarter way to compare your options?

Use the KIWIS framework:

The KIWIS framework

  • K - Kilometres: More kms amplify fuel savings and make EVs shine. Under 10,000 km/year? The petrol math improves.
  • I - Infrastructure: Secure home charging? Great. No off-street park and high public charging reliance? Budget for 60-80 c/kWh.
  • W - Wholesale energy reality: Your actual retail tariff (and whether you can charge off-peak) matters far more than national averages.
  • I - Insurance and servicing: Get live quotes. EV premiums can be higher; EV servicing is usually lower.
  • S - Sale value: Ask for a five-year trade estimate, search recent listings, and judge model-specific demand. Depreciation is the biggest swing factor.

Quick decision framework:

  • If you do 80%+ home charging and 15,000-20,000 km/year, the EV is often competitive even after RUC.
  • If you can’t home charge and you only drive 10,000-12,000 km/year, petrol may still be cheaper for now.
  • If petrol averages $3.20-$3.50/L across your ownership, EVs gain the upper hand quickly.
  • If your chosen EV is likely to hold 55% of its value at year five, it will probably beat a comparable petrol SUV on cost.

So, what’s the five‑year bill - and what should you actually do?

Here’s the base-case five-year breakdown (15,000 km/year):

  • BYD ATTO 3 (list $52,990):
    • Depreciation (to 40% residual): $31,794.
    • Running costs: about $21,935 total (charging ~$5,235; insurance ~$9,000; servicing ~$2,000; RUC ~$5,700).
    • Net ownership cost: about $53,729 (≈ $10,746/year).
  • Hyundai Kona 2.0 petrol (list $38,990):
    • Depreciation (to 45% residual): $21,444.
    • Running costs: about $26,830 total (fuel ~$15,330; insurance ~$7,000; servicing ~$4,500).
    • Net ownership cost: about $48,274 (≈ $9,655/year).

Why the gap?

  • RUC: At $76/1,000 km, an EV doing 15,000 km/year pays roughly $1,140/year. That materially reduces the EV running-cost edge.
  • Depreciation: Affordable EVs have seen sharper resale declines recently as pricing and supply shifted. If retention improves, EVs come out ahead.
  • Energy: Home electricity is still far cheaper per km than petrol, but public DC pricing erodes that advantage if you rely on it.

Sensitivity checkpoints:

  • Resale: If the Atto 3 holds 55% after five years, your EV total falls by about $10k - from underperformer to clear winner.
  • Charging split: 100% home charging at around 35 c/kWh drops EV energy to roughly $860/year, shaving about $950 off five-year costs vs our base.
  • Petrol price: Each sustained 40 c/L rise adds roughly $438 per year to the Kona’s fuel bill at 15,000 km, narrowing or flipping the gap.

Practical steps to buy with confidence:

  1. Lock in your numbers: Annual kms, access to home charging, typical home tariff (and off-peak rate), and realistic public charging share. If you’ve got solar, include it.
  2. Get quotes, not guesses: Insurance for your exact address and driver profile, both models. Ask dealers for five-year trade-in expectations and review live used listings.
  3. Price the policy landscape: EV RUC is here and predictable; the Clean Car Discount has ended. Put RUC in your annual budget now.
  4. Test your real-world charging: Try a local public charger and check pricing (per kWh or per minute) and reliability. Confirm you can install a home charger if needed.
  5. Sharpen the deal: Ask the EV dealer about warranty terms (BYD’s battery warranty can reduce downside fears), on-road costs, and any service plan. Consider asking for a guaranteed future value or strong trade-in support to de-risk depreciation.
  6. Run two scenarios: Base case plus a “stress case” with 30% public charging and conservative EV resale. If the EV still looks good, you’re safe. If not, adjust expectations or consider a different model/trim.

A few realities worth knowing:

  • RUC structure is politically debated; it improves funding fairness but dampens EV running-cost advantages.
  • Public charging prices vary and can be high; drivers without home charging bear more cost.
  • Battery warranties and emerging longevity data are reassuring, but market prices - not chemistry - set your resale.

The bottom line for 2025 NZ buyers: On our base settings (BYD ATTO 3 at $52,990 vs Kona petrol at $38,990; 15,000 km/year; 80% home charging at about 35 c/kWh; EV RUC at $76/1,000 km), the EV comes out roughly $5.5k more expensive over five years. Shift just a few levers - stronger EV resale, more home charging, higher petrol - and the EV moves into the lead. Use KIWIS to frame the choice, get your live quotes, and run your own two-scenario check. That way, whichever keys you take home, you’ll know you picked the car that fits your life and your wallet.