How we estimate the cost of owning a car.
We combine official UK vehicle data with a cost model for each category, then bring them together into one yearly figure.
Last reviewedEstimates, not guarantees
Every figure on 73 Auto is a modelled estimate. It is not a guaranteed future cost. It is not a quotation and it is not financial advice; it is informational only. Actual costs vary by the vehicle’s exact registration and condition, your location, how you drive, your specific insurance and finance circumstances, and future market changes (fuel prices, tax rules, insurance premiums). Use 73 Auto to compare and plan, not as a substitute for a real quote from an insurer, finance provider or garage.
Where a category’s model produces one, the report shows a confidence level next to the estimate, so you can see which figures rest on your own details and which on general assumptions.
Depreciation
Depreciation is the change in the car’s estimated market value over your ownership period.
- We identify the model family, generation and, where the records allow, the derivative from the car’s DVSA MOT history.
- We estimate today’s value from UK retail asking prices for comparable cars, adjusted for age and mileage. Where exact comparables are scarce, closely related cars and a calibrated age curve for the segment fill in, with more weight on more direct evidence.
- We project the value year by year over your ownership period at your annual mileage.
- Values are based on retail asking prices, not sold prices, and exclude dealer margins and selling fees.
- Each estimate carries a confidence level, down to “very low” for rare or specialist cars, and a car is only shown gaining value when the evidence for that is strong.
This is not a live valuation or a guaranteed trade-in price.
Fuel or energy
We use the most specific consumption figure available for the car, in this order:
- Your own consumption figure
- Official combined consumption
- A figure derived from official CO2 emissions
- A typical figure for the engine size
We adjust for your driving style and price it at the latest UK average pump price from the government’s weekly road fuel price statistics, or at your own price. Electric cars use energy per 100 km and a price per kWh (your own tariff, or a default). Actual spend depends on real-world driving, local prices and how the car is used.
Insurance
An estimate of the expected yearly comprehensive premium for the car and driver. It is not fetched from an insurer and it is not a quote. It is based on:
- The car’s inferred insurance group
- Local vehicle crime rates
- Your driver profile
- The expected cost of claims: injury and damage to others, damage to the car, and theft
The premium is calibrated so that across UK insured drivers it averages out to the Association of British Insurers’ published average premium paid. Every estimate has an 80% range and a confidence level. Without your details we use a standard reference driver, shown in the report, and missing details widen the range rather than raise the price. Adding your postcode, driving history and no-claims bonus on /profile narrows the range, and a real premium you enter is used instead of the estimate.
Servicing
Scheduled servicing (oil, filters, plugs, belts and fluids at the usual intervals) and the statutory MOT fee for every MOT due while you own the car. Modelled from the car’s age, class and annual mileage using typical UK servicing costs; it does not reflect a specific garage’s price list.
Brakes, suspension, batteries and other wear items are costed once, under repairs and maintenance.
Repairs and maintenance
Wear items (brake pads and discs, the 12V battery, suspension, clutch, exhaust, bulbs) and unscheduled repairs, component by component. We only cost systems the car actually has (turbocharger, gearbox type, air suspension, diesel particulate filter, hybrid or electric drive), so an electric car never carries engine or clutch costs.
- Failure rates from DVSA MOT results across tens of millions of UK tests, by age, mileage and model
- Published warranty-claim statistics
- UK parts and labour costs for the make
Repairs covered by the manufacturer’s warranty are excluded while it lasts. Advisories and failures on the latest MOT are a separate near-term allowance, and corrosion is only costed when the car’s own MOT history shows it. The figure is an expected cost with a range, not a prediction of what will fail on your car.
Tyres
We start from the likely factory tyre fitment: front and rear sizes, load and speed rating, and run-flats where fitted. If the exact wheel option is unknown, we weigh every plausible factory option and show a range.
Each size is priced as a fitted replacement (tyre, fitting, balancing, valve and disposal) using dated prices from several UK retailers, like for like rather than the cheapest online. Front and rear tyre life are estimated separately from tyre type, weight, power, drive layout, your annual mileage and driving style; tyres that age out first are replaced on age, and tyre advisories on the latest MOT count as a near-term replacement.
Vehicle tax (VED)
Calculated from official UK VED rules using the car’s CO2 emissions and first-registration date from DVLA, against the current published rate bands.
VED is the closest figure to a fixed, official cost rather than a statistical estimate. Rates and bands can change at future Budgets.
Finance
Reflects how you’re paying: cash, HP, PCP, lease or loan. Any quote, term, deposit or APR you give us is used directly. Otherwise we apply standard defaults, such as a typical term and a market-average rate for that payment type, so you still get a usable monthly figure. The confidence label shows how much rests on your own inputs. It is a modelled estimate, not a quote from a lender.
Mileage and ownership period
Several categories (depreciation, fuel/energy, servicing, repairs and tyres) scale with how much and how long you drive the car. If you don’t provide your own annual mileage or ownership period, 73 Auto falls back to standard UK driving assumptions so the report still produces a usable estimate. Entering your real annual mileage and how long you plan to keep the car makes every mileage-dependent category more accurate to your situation.
How your car and your details change the result
When you enter a UK registration we retrieve the official make, model, fuel type, engine, CO2 figure and MOT history (see Data Sources for exactly which sources are used). Each category then blends this vehicle-specific data and your inputs (postcode, insurance profile, finance details, driving style) with our cost models. Not every category returns a confidence label yet; we treat that as a gap to close, not as a sign those figures are more certain.
Quick question about accounts, pricing or reports? See the FAQ. For these cost models applied across 73 Auto's whole dataset, see UK car ownership cost statistics.
