How we calculate
Every answer on this site comes from the same calculation. Here we explain it step by step: what we leave to chance, what we hold fixed, where each number comes from and what we leave out.
How does one run work?
One run is a 36-month life of the car. For each month we settle:
- How many days the car is rented. Every month has an average: high in summer, low in winter. In each run the real count moves around that average.
- How many miles it does. On average 70 miles per rented day; this moves from month to month too.
- Whether it is damaged. The more days the car is rented, the likelier damage is. A damaged car spends 1 to 7 days in repair, and those days earn no rent.
- The money in and out. Rent comes in; maintenance, insurance, road tax, parking, damage and the loan instalment go out. Rent and costs rise with inflation; the loan instalment stays the same.
When a month's rent is more than its costs, the money left over earns savings interest until the sale. When the rent does not cover the costs, we charge the missing money the same interest. So the car and the savings are compared on equal terms.
At the end of month 36 the car is sold. We work out the sale price from today's price: the car's age, the miles above normal, the used-car market and its rental history lower the price.
What do the numbers in the result mean?
- "In how many of the 10,000 runs": the number of runs in which the car beat the bank. This number does not know the future; it only counts how many runs went well with these numbers and in this economy.
- "The typical run": the result in the middle when we sort the runs by gain. Half of the runs went better, half went worse.
- "The worst 1,000 runs": the 1,000 of the 10,000 runs that went worst. The card shows the best of these 1,000, so every one of them ended at that number or worse.
How does the economy go? Three economies
Nobody knows inflation, interest rates and used-car prices for the coming years. So we do not leave them to chance; we set out three separate economies. Each one stays fixed for the whole plan. Savings interest is before tax.
| Economy | Inflation | Savings interest | Used-car prices | Rentals in June–September |
|---|---|---|---|---|
| A: Rates drift down | 0.20% a month (2.4% a year) | 0.39% a month (4.8% a year) | -0.10% a month (-1.2% a year) | 100% of normal |
| B: Energy shock sticks | 0.27% a month (3.3% a year) | 0.43% a month (5.3% a year) | -0.20% a month (-2.4% a year) | 100% of normal |
| C: Demand shock | 0.17% a month (2.1% a year) | 0.32% a month (3.9% a year) | -0.30% a month (-3.5% a year) | 65% of normal |
- A: Rates drift down. The Bank of England's central path (July 2026 Monetary Policy Report): Bank Rate 3.75%, held on 17 Sep 2026, two hikes priced in by 2027, then cuts to about 3.5% by 2029; inflation, 3.1% in August, peaks at 3.2% late in 2026 and drops under 2% from 2028. Savings: today's 5.12% one-year fix, then about 5.0% and 4.25%, averaging about 4.8% a year, tax-free for most savers, so 0.39% a month. Inflation about 2.4% a year, 0.20% a month. Used-car prices −0.1% a month on top of ageing (Auto Trader index, September 2026: −1.0% on the year, −2.4% for 1–3-year-old cars).
- B: Energy shock sticks. The Bank's adverse scenario in the same report: oil 30% and gas 60% above the central path. Our reading of its chart: inflation peaks at about 4.5% early in 2027, is about 2.75% in 2028 and 2.4% at the end of 2029, about 3.3% a year averaged, 0.27% a month. The Bank keeps rates high (it publishes no Bank Rate for this case), so savings, already above 5.1% today, pay about 5.3% a year, 0.43% a month. Households squeezed by fuel and energy bills pay less for young used cars: −0.2% a month, one step below the expected economy.
- C: Demand shock. A recession or a travel shock: June–September bookings fall to 65%. The Bank cuts fast, to 2.5% by 2028; savings start at today's 5.12% and then fall, averaging about 3.9% a year, 0.32% a month; inflation about 2.0% a year, 0.17% a month; used-car prices take a 2008-style fall of 0.3% a month, about 10% over 3 years, on top of ageing.
Where do the numbers come from?
Every number in the calculator carries one of two tags. Source: we took it from a price list, an official rule or an industry report. Estimate: our own estimate; you can change it to your own number in the calculator. All are as of 14 October 2026.
| Number | Tag | Where from |
|---|---|---|
| Car and loan | ||
| Car price | source | Vauxhall Corsa 1.2 Turbo, the UK's most common small car: carwow cash price from £16,946 on 25 Aug 2026 (list price £20,590), rounded to £17,000. |
| Loan amount | estimate | A personal loan for 90% of the price, with £1,700 down. We pre-fill a personal loan rather than PCP or hire purchase: on those the finance company owns the car until the last payment and the agreement normally forbids renting it out, and PCP ends with a large final payment this calculator does not model. |
| Loan interest | source | A best-buy personal loan at 5.9% APR (M&S Bank 5.9%, AA 5.9% for members, Tesco 6.2% with Clubcard; MoneySavingExpert, 13 Oct 2026) costs 0.48% a month. Only half of accepted borrowers get the advertised rate; dealer finance on a used car runs 9–15% APR, 0.75–1.2% a month. |
| Loan term | estimate | Personal loans run 1 to 7 years. We cap the term at 36 months, the longest plan here. If the car is sold before the loan ends, the balance left is paid from the sale money. |
| Costs | ||
| Comprehensive insurance (own policy) | estimate | Your own comprehensive policy for the days the car is not rented; Turo insures the rental days out of its cut. MoneySavingExpert quotes for a small petrol car, Feb–Apr 2026: £374 bought early, £708 on renewal day. Tell your insurer about the car sharing: some add £0–200, a few refuse. |
| Road tax (VED) | source | Vehicle Excise Duty for a new petrol Corsa: £455 in the first year, then £200 a year (2026/27 rates, gov.uk): £285 a year averaged over 3 years. Over a 1-year plan it is £455 a year, over 2 years about £330. No MOT is due within 3 years of a new car. |
| Parking | estimate | A driveway or street parking outside London costs about nothing; a resident permit is £50–300 a year. In London an off-street bay for keyless handovers runs about £150 a month. |
| Maintenance | estimate | Per mile: servicing about 2p (£150–300 a service every 10,000 miles), tyres about 1.5p (a set of four £300–400 per 25,000 miles), brakes, bulbs and valeting between rentals about 1.5p. No fuel: renters return the car at the same fuel level. |
| Chance of damage in a month | estimate | Turo hosts report a claim or a small repair about once in 40–80 rentals. A car rented 15 days a month does about 5–7 rentals of 2–3 days: about 9% a month. This is the chance at the pack's pace (15 rented days a month); higher in a busy month, zero in a month with no rentals. Estimate. |
| Average damage cost | estimate | What you pay per event: the £250 damage responsibility on Turo's Balanced plan when a renter damages the car, or £100–400 for what the cover excludes (kerbed alloys, tyres, interior soiling). Estimate. |
| Renting | ||
| Rented days | estimate | Our estimate for a well-run listing: about 180 days a year, full in summer and sparse in winter; no platform publishes this for UK cars. Turo's average listed car is booked about 60 days a year (Turo, 2021–2022), but that average counts owners who rarely list. Turo UK's own earnings figures count small businesses from 10 trip days a month, 120 a year; Turo UK's managing director says his own car is rented about half the time (January 2026). A listing near an airport or a big city gets 18–22 days a month in summer and 12–14 in winter. Big rental firms keep their cars on rent 250–300 days a year (Hertz, Avis, 2025). |
| Daily rent (your share) | estimate | Your share after Turo's cut. Small cars on Turo list at about £28 a day in winter and £35 in July–August outside London, £28–40 in London (listings read on 25 Aug 2026). Near an airport they list higher: Corsas at Luton Airport at £41–51 a day (October 2026). On the default Balanced plan you keep 70%, so we pre-fill 70% of the listed price. |
| Average daily miles | estimate | Turo rentals average 2–3 days and renters drive well under the usual 200-mile daily allowance; 50–90 miles a day is the working range. Estimate. |
| Daily miles spread | estimate | How much the daily miles change from day to day; estimate. |
| When selling | ||
| Value after 3 years (ratio) | estimate | The share of the price you paid that a private sale brings after 3 years. Dealer listings for 2023 Corsas (cinch, Arnold Clark, 25 Aug 2026) point to about £10,000 retail for a 36,000-mile car, £9,400 in a private sale, against £17,000 paid: 0.55. After 1 year 0.75, after 2 years 0.65: dealer listings for 2025 and 2024 Corsa 1.2 Turbos (cinch, 27 Sep 2026), priced at 10,000 miles a year, less 8% for a private sale. Hybrids hold better; a Yaris is nearer 0.65. |
| Normal yearly miles | estimate | The yearly mileage the trade treats as normal; What Car? uses 12,000, and the real private average is 6,600–7,400. |
| Loss per extra 10,000 miles | estimate | Dealers and price guides take 5–8p off a £10,000 small car for each mile above normal: £500–800 per 10,000 miles, about 5% of a 3-year-old car's value. |
| “Ex-rental” discount | estimate | A peer-to-peer car stays on a private V5C with one keeper, so there is no rental mark; big-fleet ex-hire cars fetch 3–5% less at auction, mostly for condition. Estimate. |
What do we leave out?
- Both sides are before tax: we took no income tax off the rental profit and none off the savings interest; with one car and about £17,000 saved, most people pay little or none on either. The daily rent is your share after Turo's cut.
- The renter pays for fuel; it is not in the calculation.
- The car is sold at the end of month 36, at once, at the price we work out.
- Every month counts as 30 days. Rent and costs rise with the same inflation.
- We charge a month's missing money the savings interest. A real loan could cost more.
Who makes it?
BuyOrBank is a free tool by Novel Yazılım, a software company in Turkey. No account, no ads, no tracking. Why we made it and who pays for it: Who we are. If you find a wrong number, write to info@novelyazilim.com; we correct it and update the date at the top.
Try it with your own numbers: enter the car's price, your loan and the daily rent. The answer uses the same 10,000 runs, in the economy you choose. Free, no sign-up.
Car or bank? calculatorSources
- The source of every number: the "Where from" column of the table above.
- The economies' sources: the economy notes (Bank of England Monetary Policy Report, ONS consumer price inflation, Auto Trader's used-car price index, MoneySavingExpert's best-buy savings tables).
This page is not investment advice. When the numbers change, we update the page; the date is at the top.