The used electric car market has changed shape. The number that decides what a second-hand EV is worth is no longer the mileage on the clock — it is how much of its battery is left.
Quick answer: Battery State of Health (SoH) — the percentage of original capacity a battery retains — is now the single biggest determinant of a used EV's price, ahead of mileage or age in many cases. Used EV prices fell nearly 10% year on year into 2026, and three-year depreciation runs at 38-42% against 35-40% for petrol. That makes 2026 a strong buyers' market, provided you check SoH before you commit.
Why battery health became the price
For a petrol car, condition is spread across the whole vehicle. For an EV, one component represents a large share of the value — and unlike an engine, it degrades measurably and reports its own condition.
Two cars of the same model, year and mileage can now carry meaningfully different prices purely on SoH. Trade buyers price it explicitly, and increasingly so do private ones.
What the numbers mean
| SoH | What it indicates |
|---|---|
| 95%+ | Excellent — typically a low-mileage or gently used car |
| 90-95% | Strong for a 3-4 year old EV |
| 85-90% | Normal ageing; expect it on higher-mileage examples |
| Below 85% | Investigate — reasonable on an older car, a red flag on a young one |
| ~70% | The level most manufacturer warranties guarantee for 8 years / 100,000 miles |
A car at 90% SoH does not have a fault. It has 90% of its original range — so a nominal 250-mile EV realistically covers around 225 miles in the same conditions.
How to check it before you buy
Three routes, in order of reliability:
- An independent battery health certificate. Increasingly common on forecourts and the strongest evidence. Ask whether one exists before you travel.
- The car's own service menu. Many manufacturers expose SoH in the vehicle's diagnostics or companion app.
- A third-party OBD diagnostic tool. Plugs into the car's port and reads the battery management system directly.
If a seller cannot or will not produce an SoH figure by any of these routes, treat that as information in itself. On a 2026 used EV it is the most important number on the car, and its absence is rarely accidental.
Why used EV prices have fallen
Used EV values fell nearly 10% year on year into 2026. The main driver is not a problem with the cars — it is pressure from the new market.
The ZEV mandate requires manufacturers to sell a rising share of electric cars. To hit those targets, carmakers have discounted new EVs aggressively. Every discount on a new car immediately drags down the value of the equivalent two-year-old one, because a used car has to look like value against the new price, not the old one.
| Three-year depreciation | Typical range |
|---|---|
| Electric | 38-42% |
| Equivalent petrol | 35-40% |
Industry data from Cox Automotive and Cap HPI.
The gap is real but narrower than the headlines often suggest — a few percentage points, not a different universe.
Winners and losers
Depreciation is not uniform across brands.
Holding value comparatively well: Tesla's Model 3 and Model Y, helped by over-the-air software updates that keep older cars feeling current, Supercharger network access, and strong real-world battery longevity.
Falling hardest: cars from manufacturers that have retreated from or withdrawn from the UK market. Buyers price in uncertainty about parts, software support and warranty, and that discount can be steep. If you are buying a brand you have not heard much about lately, check it still has a UK presence.
Why this is a good market to buy into
The conditions that hurt sellers help buyers:
- Abundant supply as early adopters and fleets cycle out of three-year-old cars.
- Real competition between sellers, which is negotiable in a way it was not in 2022.
- Prices well below the inflated levels of 2021-22.
For a buyer with home charging, a well-chosen used EV at 90%+ SoH is one of the cheapest ways to run a car in Britain right now.
Run the running costs before you decide
The purchase is only half the sum. As of 28 August 2026, UK petrol averaged 160.9p a litre and diesel 180.5p (live figures) — so a 10,000-mile-a-year petrol driver at 40mpg is spending roughly £1,830 a year on fuel alone.
Against that:
- Home charging on an off-peak EV tariff is typically a fraction of the petrol figure — see cost to charge an EV at home.
- Public rapid charging only can cost more per mile than petrol — see public EV charging costs.
The single biggest question for a used EV buyer is not which model, it is whether you can charge at home. If you can, the case is strong. If you cannot, model your real mileage on the journey cost calculator before committing, and compare against what you would spend at today's pump prices.
Also factor the tax direction: fuel duty is rising from September 2026, while a pay-per-mile EV tax arrives in April 2028. Both fuels get dearer; neither change is large enough to flip the home-charging maths on its own.
A used EV buying checklist
- Get the SoH figure in writing before you travel.
- Check remaining battery warranty — typically 8 years / 100,000 miles to around 70%.
- Confirm the brand still has a UK presence for parts and support.
- Check charging speed, not just range — an older EV may cap at a low rapid-charge rate.
- Confirm you can charge at home, or price public charging honestly.
- Keep the MOT and tax dates tracked once you buy — EVs need an MOT from three years old, exactly like petrol cars.
The bottom line
Battery State of Health is the price. Get the number, compare it against the car's age and the warranty floor, and you have removed most of the risk from a used EV purchase.
The market itself is on your side: supply is plentiful, prices have fallen nearly 10% year on year, and competition is genuine. Just make sure the running-cost case works for how you charge — and see what you are currently spending on the live fuel price map.
Depreciation and market figures reflect industry reporting from Cox Automotive, Cap HPI and market analysis as of 28 August 2026. Live pump averages from the UK Government Fuel Finder scheme via Fuel Near You.
Frequently Asked Questions
What is battery State of Health on an electric car?
State of Health (SoH) is the percentage of its original usable capacity a battery still holds. A three-year-old EV showing 92% SoH retains 92% of the range it had when new. It has become the single biggest determinant of a used EV's price in 2026 — in many cases more influential than mileage or age.
How do I check the battery health of a used electric car?
Ask the seller for a battery health certificate from an independent test, check the car's own service menu where the manufacturer exposes SoH, or use a third-party OBD diagnostic tool. Treat a seller who will not provide any SoH figure as a warning sign — on a 2026 used EV it is the most important number on the car.
How much do electric cars depreciate in the UK?
Industry data from Cox Automotive and Cap HPI puts average EV depreciation at 38-42% after three years, compared with 35-40% for equivalent petrol cars. Used EV prices fell nearly 10% year on year into 2026, driven largely by manufacturers discounting new EVs to meet ZEV mandate targets.
Is 2026 a good time to buy a used electric car?
For buyers, yes. Abundant supply, genuine competition between sellers and prices that have not returned to the inflated 2021-22 levels make it one of the most favourable used EV markets in years. The trade-off is that you are buying into a falling market, so battery condition and model choice matter more than ever.
What is a good battery State of Health for a used EV?
As a rough guide, above 90% is strong for a car three to four years old, 85-90% is normal, and below 85% on a relatively young car warrants investigation. Compare against the manufacturer's battery warranty, which typically guarantees around 70% capacity for 8 years or 100,000 miles.
Which used EVs hold their value best?
Tesla's Model 3 and Model Y have continued to hold values comparatively well, helped by over-the-air software updates, Supercharger network access and strong real-world battery longevity. Cars from brands that have retreated from or withdrawn from the UK market tend to depreciate most sharply, as buyers price in uncertainty over parts and support.