Vehicles calculators

A car is sold by its purchase price and judged by its monthly payment, but neither of those numbers is the cost of ownership. The full cost is a stack: purchase price, depreciation, finance interest, fuel, insurance, registration, servicing, repairs, tyres, parking, tolls, and the residual value at sale. Compressed across a typical 6-year ownership window, the total cost is usually 1.5–2.5x the headline sticker price.

These calculators expose that stack. Whether you are comparing two vehicles head-to-head, evaluating a lease versus a purchase, modelling fuel cost for a long commute, or testing whether an EV's higher purchase price is offset by running savings, the engine returns the same set of unbranded numbers: total cost of ownership, cost per kilometre, depreciation curve, and the residual at any year of the holding period.

All maths uses 20-digit decimal precision. We treat fuel prices, electricity tariffs, and registration costs as user-supplied parameters rather than country-specific defaults, so the same calculator works regardless of jurisdiction.

Total cost of vehicle ownership

Total cost of ownership (TCO) for a vehicle is the sum of its capital and operating costs over the holding period, less the residual value at sale. The capital side is dominated by depreciation — typically 50–70% of the purchase price across the first 5 years for an internal combustion vehicle, more for luxury, less for commercial. The operating side is dominated by fuel for high-mileage drivers and by insurance + financing for low-mileage drivers.

A useful rule: divide TCO by total kilometres driven to get cost per kilometre. The number lands between $0.30/km for a small efficient hatchback driven 30,000 km/year and $1.50/km for a luxury vehicle driven 8,000 km/year. The rate is the most useful single metric for comparing vehicles, because it normalises across vehicle class, age, and usage pattern.

The total-ownership-cost calculator runs the full stack and produces both the TCO and the cost per kilometre. Run it before you sign — the same vehicle bought new typically costs 30–50% more in TCO terms than the equivalent 3-year-old used vehicle, even after accounting for higher repair costs on the older car.

Depreciation — the largest hidden cost

Depreciation is the single largest cost of vehicle ownership for most buyers, and the most invisible one. Unlike fuel or insurance, no monthly bill arrives — the cost is realised only at sale, when the difference between what you paid and what you receive becomes painfully concrete. A $50,000 vehicle losing 50% of its value in 5 years costs you $5,000 per year in depreciation alone, before you've turned the key.

Depreciation is steepest in the first year (typically 15–25% of purchase price) and tapers thereafter. By year 8–10 the curve has flattened to a few percent per year. The depreciation calculator plots this curve so you can see the cost of selling at year 1 versus year 5 versus year 10.

The implication: matching ownership length to depreciation curve is the most powerful TCO lever. Buying a 3-year-old vehicle and holding it to year 8 captures only the flat portion of the curve, dramatically reducing the depreciation cost per year. The new-vs-used calculator compares both strategies head-to-head with the same TCO methodology.

Fuel and running costs

Fuel cost is a function of three numbers: distance, fuel consumption (l/100km or mpg), and fuel price. The fuel-cost calculator combines them into an annual fuel bill and a cost per kilometre — useful for comparing two vehicles, or for modelling the impact of a fuel-price spike on your transport budget.

A 20% improvement in fuel efficiency on a typical 15,000 km/year usage saves roughly $400–$800 per year at common fuel prices. Across a 7-year ownership period, that's $3,000–$5,500 — meaningful, but rarely large enough to justify a $10,000+ price premium for an efficient vehicle on fuel savings alone.

Electric vehicles change the arithmetic. An EV's "fuel" cost is electricity, typically 25–50% of the equivalent petrol cost per kilometre when charged at home. The EV-savings calculator runs the comparison directly: at typical mileages and tariffs, the lifetime fuel saving is $10,000–$20,000, which can offset a meaningful share of the higher purchase price. The ICE-to-EV upgrade calculator extends this to the question of whether replacing an existing vehicle now beats running it to end-of-life.

Buying decisions

Beyond the new-vs-used decision, two structural choices dominate the cost of vehicle ownership: leasing versus buying, and owning versus using public transport. Both decisions can be modelled in dollar terms once the full cost stack is included.

A lease is a long-term rental: you pay a monthly fee for the use of the vehicle but never own it. Leases lower the monthly cost and isolate you from depreciation risk, but the total cost over a long ownership horizon is typically higher because you pay for the most expensive years of the vehicle (the early high-depreciation years) repeatedly. The lease-vs-buy calculator runs both paths over a configurable horizon — for buyers who keep vehicles 7+ years, ownership almost always wins; for buyers who upgrade every 3 years, leasing is closer.

The most under-considered comparison is owning versus public transport. For inner-city commuters with reliable public transport access, the cost of a private vehicle — TCO around $8,000–$15,000/year — is typically 3–5x the cost of a public-transport pass plus occasional ride-shares. The own-vs-public-transport calculator runs the comparison for your specific commute and usage pattern. Even if you ultimately choose ownership, the comparison clarifies what you are paying for.

When to replace versus repair an existing vehicle

Once a vehicle is owned, the most common financial decision is whether to keep repairing it or replace it. The classic heuristic is the repair-cost ratio: when an annual repair bill exceeds roughly 50% of the vehicle's current resale value, replacement starts to win on a per-year-of-future-ownership basis. Below about 30%, repair almost always wins because the depreciation on a replacement vehicle is the larger annual cost. The 30–50% range is where context — reliability history, expected remaining useful life, scarcity of parts — decides the outcome.

The depreciation curve makes the trade-off mostly arithmetic. A 12-year-old vehicle worth $4,000 has another year or two of structural depreciation left and very little after that — even a $2,000 repair leaves the owner ahead of any replacement that introduces $5,000+ in year-one depreciation alone. The same $2,000 repair on a 4-year-old vehicle worth $25,000 looks similar in absolute dollars but very different on the depreciation comparison: the 4-year-old vehicle still has years of steep depreciation ahead, so the per-year cost gap between repair and replacement narrows. The total-ownership-cost calculator combined with the depreciation calculator quantifies both paths over a configurable horizon.

The non-financial side of the decision is unreliability. A vehicle that strands the owner once a quarter imposes costs that don't show up on any spreadsheet — missed appointments, ride-share surcharges, the cognitive overhead of wondering whether today's drive will end at a tow yard. When unreliability is recurring rather than isolated, replacement is usually justified regardless of the repair-cost ratio. The financial calculation matters most when the vehicle is fundamentally sound and one or two large repairs have surfaced — the case where the math is close enough that the answer matters.