Battery degradation — what studies actually say

We only quote figures tied to a named study or OEM report. Your car may do better or worse.

Multi-brand fleet studies

• Geotab (updated study, 22,700+ EVs, 21 makes). Average annual degradation about 2.3% per year. Vehicles that relied heavily on DC fast charging above 100 kW averaged up to about 3.0%/year versus around 1.5%/year for mostly lower-power / AC charging. Hot climates added roughly 0.4%/year versus mild climates in their split. Source: Geotab press release (retrieved Nov 2026).
• Generational 2025 Battery Performance Index (UK). Analysis of 8,000+ UK battery health tests in 2025; report states average battery health about 95.15% across the sample, with median health still around 85% in older age bands (8–9 years cited in the report summary). Individual results vary — that variance is the point of testing. PDF: Generational 2025 BPI.

Tesla-specific published figures

• Tesla’s Impact Reports have published fleet capacity retention charts for older S/X and 3/Y packs (commonly summarised in the trade press as on the order of low-teens percent loss by ~200,000 miles). Always read the latest Impact Report chart axis yourself rather than a screenshot with no year.
• Recurrent has published Tesla-focused range retention blogs (Model 3/Y by age). Treat them as observational US data, not a warranty.

Warranty vs “feels lower”

Tesla’s UK new-vehicle warranty documents set battery capacity commitments for a period/mileage — read the current PDF on Tesla UK Support. A cold morning range drop is often temperature, not permanent loss (winter range).

Habits that studies flag

• Prefer AC / home charging for daily miles when you can; save high-power DC for trips.
• Avoid sitting for weeks at 100% or 0% when you have a choice.
• Precondition before DC in the cold.

Buying used? Used Tesla checklist.