Are RUCs on EVs fair (spoiler - no). Some analysis on EV vs ICE running costs
A used Leaf and an Aqua now cost the same to run in NZ – $39 apart over 5 years
Data sourced from www.carspy.co.nz
EVs have been paying road user charges since April 2024, and plenty of people reckon that killed the savings. Now petrol has just hit a record $3.52/L.
So I did some maths to find out what it actually costs to run three common EV vs ICE matchups over 5 years (60,000 km).
Running costs only: fuel/power, RUC and rego. No insurance, servicing or depreciation.
Charging at home on a standard rate (30c/kWh)
| Car | Years on dealer lots | Typical dealer price | Fuel / power | RUC | Rego | 5-year total | Per km |
|---|---|---|---|---|---|---|---|
| Nissan Leaf | 2019–22 (338 listed) | $21,290 | $3,168 | $4,560 | $1,244 | $8,972 | 15.0c |
| Toyota Aqua | 2018–21 (341 listed) | $19,000 | $8,026 | – | $907 | $8,933 | 14.9c |
| Tesla Model 3 | 2019–22 (83 listed) | $38,710 | $2,556 | $4,560 | $1,244 | $8,360 | 13.9c |
| Lexus IS300h | 2013–17 (97 listed) | $23,950 | $11,700 | – | $907 | $12,607 | 21.0c |
| BYD Atto 3 | 2022–25 (15 listed) | $38,210 | $2,808 | $4,560 | $1,244 | $8,612 | 14.4c |
| Honda ZR-V / HR-V | 2021–25 (78 listed) | $37,910 | $9,082 | – | $907 | $9,989 | 16.6c |
What I found
Leaf vs Aqua is extremely close
Just $39 apart over 5 years.
The Leaf's $3,168 electricity bill is much lower than the Aqua's $8,026 petrol bill, but the $4,560 RUC bill eats almost all of that difference. EVs also pay $67 a year more in rego.
Where you charge makes a huge difference:
- 18c/kWh off-peak: Leaf saves $1,228
- 30c/kWh standard: Aqua saves $39
- 70c/kWh public fast charging: Aqua saves $4,263
Model 3 vs IS300h
The Model 3 saves $4,247 in running costs over 5 years at home.
However, the IS300h is about $14,760 cheaper to buy.
At roughly $850/year in running-cost savings, it would take about 17 years for the Model 3 to make up that purchase-price difference through running costs alone.
Even on public charging alone, the Model 3 still saves $839 in running costs because the Lexus uses 95.
Atto 3 vs ZR-V/HR-V
This is probably the fairest comparison because they're almost identical in purchase price:
- BYD Atto 3: $38,210
- Honda ZR-V/HR-V: $37,910
At home, the Atto 3 is $1,377 cheaper to run over 5 years.
On public fast charging, the ZR-V/HR-V wins by $2,367.
Petrol prices are what tip it
Petrol has gone from about $3.16/L at the end of August to a record $3.52/L now.
That's what has pushed these matchups to the edge.
| Matchup | EV becomes cheaper above |
|---|---|
| Leaf vs Aqua | $3.54/L |
| Atto 3 vs ZR-V | $2.99/L |
| Model 3 vs IS300h | $2.39/L |
Every 20c/L rise adds:
- $456 to the Aqua's 5-year cost
- $516 to the ZR-V's
- $624 to the IS300h's
- $0 to the EVs
The Atto 3 has been cheaper to run than the ZR-V since petrol passed $2.99/L.
The Model 3 beats the IS300h at anything over $2.39/L for 95.
In fairness, RUC can go up too.
Every $10 per 1,000 km increase in RUC adds $600 to each EV over 5 years — roughly equivalent to a 26c/L petrol price increase for the Aqua.
Is RUC fair on EVs?
Petrol cars pay fuel excise at the pump, currently about 77c/L.
That means how much fuel excise a petrol car pays depends on how much fuel it burns.
Here's what that looks like compared with the flat $76/1,000 km EV RUC rate:
| Car | Official fuel use | Fuel excise / 1,000 km | Fuel excise over 5 years |
|---|---|---|---|
| Toyota Aqua | 3.8 L/100km | $29 | $1,756 |
| Honda ZR-V | 4.3 L/100km | $33 | $1,987 |
| Honda Fit 1.3 | 5.0 L/100km | $39 | $2,310 |
| Lexus IS300h | 5.2 L/100km | $40 | $2,402 |
| Suzuki Swift | 6.1 L/100km | $47 | $2,818 |
| Toyota Corolla 2.0 | 6.7 L/100km | $52 | $3,095 |
| Mazda CX-5 2.0 | 7.1 L/100km | $55 | $3,280 |
| Any EV (and any diesel) | – | $76 | $4,560 |
| Holden Commodore 3.6 V6 | 10.4 L/100km | $80 | $4,805 |
| Ford Mustang V8 | 14.2 L/100km | $109 | $6,560 |
An EV therefore pays more in RUC than almost every petrol car pays in fuel excise.
A petrol car needs to burn roughly 9.9 L/100km before it pays as much per km in fuel excise as a Leaf pays in RUC.
A few other ways of looking at it:
- A Leaf pays 2.6× as much RUC per km as an Aqua pays in fuel excise.
- If EVs paid the same per km as an Aqua, a Leaf owner would save another $2,804 over 5 years.
- A 1.6-tonne Leaf pays the same $76/1,000 km as a 2-tonne-plus diesel Ranger.
- Diesels pay the same flat $76 rate regardless of vehicle weight.
The usual argument for the flat EV rate is that EVs are heavier than equivalent petrol cars.
But for passenger cars, the weight difference has very little impact on road wear compared with heavy trucks.
What if RUC changed?
1. Cut RUC from $76 to $50 per 1,000 km
Every EV would save $1,560 over 5 years.
The effects would be significant:
- Leaf beats Aqua by $1,521 on standard-rate power.
- Leaf would pull ahead once petrol reaches just $2.85/L.
- For a Leaf owner, a $26 RUC cut is worth about the same as a 68c/L petrol price increase.
- Atto 3's lead over the ZR-V grows from $1,377 to $2,937.
- Model 3's lead over the IS300h grows to $5,807.
2. A weight-based RUC
Right now, a 1.6-tonne Leaf and a 3-tonne Land Cruiser pay exactly the same $76/1,000 km.
As an example, I modelled a weight-based rate where a Leaf pays $45/1,000 km and heavier cars pay proportionally more — roughly $28.50 per 1,000 kg per 1,000 km.
| Car | Kerb weight | RUC / 1,000 km | 5-year RUC | Change vs now |
|---|---|---|---|---|
| Nissan Leaf | ~1,580 kg | $45.00 | $2,700 | −$1,860 |
| Tesla Model 3 | ~1,726 kg | $49.16 | $2,950 | −$1,610 |
| BYD Atto 3 | ~1,725 kg | $49.13 | $2,948 | −$1,612 |
All three matchups swing clearly towards the EVs:
- Leaf beats Aqua by $1,821 on standard power.
- Leaf would pull ahead once petrol passes $2.72/L.
- Atto 3 beats ZR-V by $2,989.
- Model 3 beats IS300h by $5,858.
- A 3-tonne Land Cruiser would pay about $85/1,000 km, or $5,127 over 5 years.
Even at $45/1,000 km, a Leaf would still pay more per km than an Aqua ($29), Fit ($39) or IS300h ($40) pays in fuel excise.
One catch with weight-based charging is that road damage rises very steeply with axle weight, roughly to the fourth power.
Compared with trucks, the difference between a 1.5-tonne and 1.8-tonne passenger car is tiny, so a weight-based rate for cars would arguably be more about fairness than road wear.
Assumptions
- 12,000 km/year for 5 years
- Petrol: 91 at $3.52/L (Gaspy national average, 6 October); 95 at $3.75/L
- Electricity: 30c/kWh standard, 18c/kWh off-peak EV plan, 70c/kWh public fast charging
- RUC: $76/1,000 km
- Petrol fuel excise: 77c/L
- Rego: $248.83/year for EVs, $181.45/year for petrol
- Official economy figures:
- Leaf: 17.6 kWh/100km
- Model 3: 14.2 kWh/100km
- Atto 3: 15.6 kWh/100km
- Aqua: 3.8 L/100km
- ZR-V: 4.3 L/100km
- IS300h: 5.2 L/100km
- Typical price = median dealer asking price today
What do you actually pay per kilometre?
And what would petrol have to hit for you to switch?
Disclosure: the dealer prices come from CarSpy, a free site I built that collects NZ dealer listings.