Analysis of 2,000 used plug-in hybrid and battery-electric vehicles from automotive retailers finds PHEVs have a wider spread of battery State of Health, despite broadly similar average battery performance.
Data underscores the importance of battery transparency in used plug-in market.
- Generational analysis of 2,000 used plug-in vehicles finds both PHEVs and BEVs retain strong average battery health.
- PHEVs averaged 94.27% SoH, compared with 94.94% for BEVs.
- PHEV battery health showed greater variation, with 5.48% SoH standard deviation versus 4.14% for BEVs.
- 4.70% of PHEVs fell below 85% SoH, compared with 1.50% of BEVs.
- The wider PHEV spread likely reflects more varied real-world usage and charging behaviour between both vehicle-types – underscoring the importance of condition transparency.
- High-resolution imagery can be downloaded here.
Generational, the UK-based innovator in electric vehicle battery condition diagnostics, has published new analysis comparing battery performance across used plug-in hybrid electric vehicles (PHEVs) and battery-electric vehicles (BEVs) from automotive retailers across the country.
The analysis, covering 1,000 PHEVs and 1,000 BEVs of comparable age and mileage, found that both vehicle sets retained strong average battery State of Health (SoH). However, Generational observed materially greater variation among PHEVs, suggesting that PHEV battery performance may be more heavily shaped by differing usage profiles, charging behaviour and driving patterns than those seen in BEVs.
Across the PHEV cohort, average SoH stood at 94.27%, with a standard deviation of 5.48%. By comparison, the BEV cohort recorded a slightly higher average SoH of 94.94%, with a lower standard deviation of 4.14%.
Generational also found that 4.70% of PHEVs in the sample had an SoH below 85%, compared with 1.50% of BEVs. While the proportion of lower-performing vehicles remains small across both groups, PHEVs were more than twice as likely to fall below that threshold within this dataset.
The findings point to a notable difference in how PHEVs and BEVs are used in the real world. BEVs are generally dependent on the battery as the vehicle’s primary energy source, meaning owners and operators typically develop more consistent charging and usage routines.
PHEVs, by contrast, can be used in a wider range of ways; some are charged frequently and driven largely on electric power, while others may rely more heavily on the combustion engine, or may experience shallower, more frequent charge and discharge cycles.
As a result, two PHEVs of similar age and mileage may have very different battery histories. This makes verified battery testing an essential part of the decision-making process for retailers, remarketers, financiers and buyers seeking to understand the true condition of a used plug-in vehicle.
Oliver Phillpott, CEO of Generational, said: “Average state of health evidently remains strong across both PHEVs and BEVs. What stands out is the wider spread of results among PHEVs, which underscores how both buyer and seller need to double down on checking the usage profile of the vehicle in question.
“Even while the averages are reassuring, for both parties the data reinforces how battery condition is something that needs to be assessed on a case-by-case basis. Transparent testing allows strong vehicles to be priced confidently and problematic vehicles to be identified early. So, across both segments, retailers and consumers can go into the market confident of finding a robust vehicle to meet their needs.”
The new PHEV-versus-BEV analysis follows the publication of Generational’s 2025 Battery Performance Index. Based on more than 8,000 battery health assessments conducted in 2025, the Index found average battery health of 95.15% across tested vehicles, with even 8-9-year-old vehicles retaining around 85% median capacity, comfortably above common OEM warranty thresholds. It also found that high-mileage EVs with 100,000+ miles frequently returned 88-95% SoH, challenging the assumption that mileage alone is a reliable predictor of battery condition.
The Battery Performance Index concluded that battery degradation is not the systemic risk it is often assumed to be, but that variance between individual vehicles becomes more important as vehicles age. It also argued that uncertainty, rather than underlying battery longevity, is now one of the principal constraints on used EV confidence, residual values and transaction efficiency.
Phillpott added: “The used EV and PHEV market is entering a rapid growth phase. Buyers increasingly understand that the battery is the most valuable component in the vehicle, but they still need clear, trusted information before they can buy with confidence.
“Our latest analysis shows why a single mileage or age figure cannot tell the whole story. Battery condition is becoming the defining factor in used plug-in vehicle value, and the industry now has the data and tools to make that condition visible.”
Generational’s battery health checks and State of Health certification are designed to help retailers, leasing companies and remarketers assess used EV batteries quickly and consistently. The company says its tools enable retailers to certify battery health and real-world range, support stronger buyer confidence and reduce risk when acquiring, valuing and selling used plug-in vehicles.
Notes to Editors
Generational’s recently published Battery Performance Index can be downloaded here, with high-resolution imagery here.
About the analysis
Generational analysed battery State of Health data from used plug-in vehicles supplied by automotive retailers across the country. The dataset comprised:
PHEV cohort
Count: 1,000 vehicles
Average SoH: 94.27%
Standard deviation SoH: 5.48%
Share with SoH below 85%: 4.70%
BEV cohort
Count: 1,000 vehicles
Average SoH: 94.94%
Standard deviation SoH: 4.14%
Share with SoH below 85%: 1.50%
About the 2025 Battery Performance Index
The Index is based on more than 8,000 battery health assessments conducted in 2025 across the UK used EV market, covering:
- 0-12-year-old vehicles (2013–2025 model years)
- 0-160,000+ miles
- 36 manufacturers
- Passenger BEVs, PHEVs and LCVs
The report will be published annually, establishing a recurring national benchmark for battery condition in the UK.
About Generational
Generational is a UK-based innovator in electric-vehicle battery-condition testing solutions. The business provides simple, intuitive electric-vehicle battery-condition checks and state-of-health (SoH) certification services to car dealers and remarketers.
Generational was founded by a team of automotive software engineers and data scientists with deep expertise in EV technology, from Red Bull Racing, Imperial College London, and the University of Cambridge.
Its ultimate mission is to facilitate a thriving market for used EVs – helping businesses sell vehicles faster and more profitably, maximise residual value, and build a robust business-case for investing in the pre-owned EV market.
Further information on Generational’s solutions can be found on its website here.
