All assumptions and values
Every hardcoded number in the calculator, listed so you can verify or challenge them.
Fixed annual costs
| Item | Value |
|---|---|
| Registration | $110/year |
| WoF | $60/year |
| RUC (diesel) | $76 per 1,000 km |
| RUC (EV) | $76 per 1,000 km |
| RUC (petrol) | $0 (included in fuel excise) |
Maintenance base costs
| Item | Value |
|---|---|
| ICE base maintenance | $800/year (before vehicle factor) |
| Tesla base maintenance | $400/year |
| ICE age scaling | +15% per year above age 3 |
| Tesla age scaling | +8% per year above age 4 |
| ICE km scaling | +0.3% per 1,000 km above 100k |
| Tesla km scaling | +0.2% per 1,000 km above 100k |
Tyre costs
| Vehicle | Set cost | Replacement interval |
|---|---|---|
| ICE | $800 | 50,000 km |
| Tesla | $1,500 | 40,000 km |
Tesla energy efficiency
| Model | kWh/100km |
|---|---|
| Model 3 | 14.5 |
| Model Y | 16.0 |
Depreciation confidence band
| Scenario | Rate adjustment |
|---|---|
| Optimistic | Base rate x 0.75 |
| Moderate | Base rate (as listed) |
| Pessimistic | Base rate x 1.25 |
Km adjustment (+0.05% per 1,000 km above 80,000 km, capped at 25% total) is applied on top of all scenarios. Import adjustment (0.8x rate) applies before the scenario multiplier.
Per-vehicle data
Depreciation rates, maintenance factor, and typical fuel consumption for each listed vehicle.
| Vehicle | L/100km | Maint. | Import adj. | Dep. rates (by age) |
|---|---|---|---|---|
| Toyota Corolla | 6.8 | 0.8x | 0.8x | 14% / 10% / 7% / 5% / 3% |
| Toyota Camry | 7.8 | 0.85x | 0.8x | 15% / 10% / 7% / 5% / 3% |
| Mazda 3 | 6.5 | 0.85x | 0.8x | 15% / 10% / 7% / 5% / 3% |
| Mazda 6 | 7.5 | 0.9x | 0.8x | 16% / 11% / 7% / 5% / 3% |
| Honda Civic | 6.8 | 0.8x | 0.8x | 14% / 10% / 7% / 5% / 3% |
| Honda Fit / Jazz | 5.8 | 0.7x | 0.8x | 15% / 10% / 7% / 5% / 3% |
| Suzuki Swift | 5.5 | 0.7x | 0.8x | 15% / 10% / 7% / 5% / 3% |
| Subaru Impreza | 7.2 | 1x | 0.8x | 16% / 11% / 7% / 5% / 3% |
| Toyota RAV4 | 7.8 | 0.85x | 0.8x | 13% / 9% / 7% / 5% / 3% |
| Mazda CX-5 | 7.4 | 0.9x | 0.8x | 14% / 10% / 7% / 5% / 3% |
| Mitsubishi Outlander | 8 | 0.9x | 0.8x | 16% / 11% / 7% / 5% / 3% |
| Honda CR-V | 7.6 | 0.85x | 0.8x | 14% / 10% / 7% / 5% / 3% |
| Nissan X-Trail | 8.2 | 0.9x | 0.8x | 16% / 11% / 7% / 5% / 3% |
| Subaru Outback | 7.7 | 1x | 0.8x | 14% / 10% / 7% / 5% / 3% |
| Toyota Hilux (diesel) | 10.5 | 1.2x | - | 10% / 8% / 6% / 4% / 3% |
| Ford Ranger (diesel) | 10.8 | 1.2x | - | 13% / 9% / 7% / 5% / 3% |
| Hyundai i30 | 7 | 0.85x | - | 17% / 12% / 8% / 5% / 3% |
| Kia Cerato | 7.2 | 0.85x | - | 17% / 12% / 8% / 5% / 3% |
| Hyundai Tucson | 8 | 0.9x | - | 16% / 11% / 8% / 5% / 3% |
| Kia Sportage | 7.8 | 0.9x | - | 16% / 11% / 8% / 5% / 3% |
| Volkswagen Golf | 6.5 | 1.3x | - | 20% / 13% / 9% / 6% / 4% |
| BMW 3 Series | 7.5 | 1.5x | - | 20% / 14% / 9% / 6% / 4% |
| Audi A3 | 6.8 | 1.4x | - | 20% / 13% / 9% / 6% / 4% |
| Mercedes C-Class | 7.8 | 1.6x | - | 20% / 14% / 9% / 6% / 4% |
Depreciation rates read left to right: age 0-2 / 3-5 / 6-8 / 9-12 / 13+
Tesla depreciation rates
| Model | Dep. rates (by age) |
|---|---|
| Tesla Model 3 | 18% / 12% / 8% / 5% / 3% |
| Tesla Model Y | 16% / 11% / 8% / 5% / 3% |
Depreciation rates read left to right: age 0-2 / 3-5 / 6-8 / 9-12 / 13+
Default input values
| Input | Default |
|---|---|
| Current car | Toyota Corolla, NZ New |
| Current car fuel | Petrol, $3.38/L, 6.8 L/100km |
| Current car year | 2018 |
| Current car odometer | 80,000 km |
| Current car value | $15,000 |
| Current car insurance | $1,200/year |
| Km driven per year | 12,000 km |
| Tesla model | Model 3 |
| Tesla year | 2023 |
| Tesla odometer | 20,000 km |
| Tesla price | $45,000 |
| Tesla insurance | $1,800/year |
| Electricity price | $0.30/kWh |
| Opportunity cost rate | 5.5% |