This is the specification trap on the UX 300e, and it is the largest usable-versus-gross gap of any electric car in our data.
The first Australian UX 300e is sold as a 54.3 kWh car. The usable capacity is 45 kWh. That is a 9.3 kWh gap — about 17% of the headline number that you will never access.
The later car is sold as 72.8 kWh with 64 kWh usable — an 8.8 kWh gap.
Any range calculation done on the advertised figure is wrong before you account for a single percentage point of degradation. Lexus is being conservative, and a large buffer at both ends of the charge window is one reason these packs should age well — but the number you plan around is the usable one.
The packs Australia got
| Variant | Years | Usable kWh | Gross kWh | Claimed range | Real-world consumption |
|---|---|---|---|---|---|
| UX 300e (54.3 kWh) | 2021–2023 | 45.0 | 54.3 | 315 km | 19.1 kWh/100km — modelled |
| UX 300e (72.8 kWh) | 2023–2025 | 64.0 | 72.8 | 450 km | 18.8 kWh/100km — modelled |
45 kWh usable at a modelled 19.1 kWh/100 km is roughly 236 km real-world against a 315 km claim. For a premium compact SUV that is a short leash, and it is worth knowing before rather than after.
The warranty position
Lexus's 70% capacity floor applies to the RZ, its battery-electric SUV — not to the UX 300e's era of cover. Lexus's hybrid, plug-in and EV traction battery cover is 5 years unlimited kilometres, extendable to 10 with an annual Traction Battery Health Check, and capacity degradation is not covered.
Lexus also does not publish a transferability statement, and its terms state that measurement methods and replacement decisions rest solely with Lexus Australia. Full detail: Lexus battery warranty in Australia.
What to check before you buy
Which pack — 45 or 64 kWh usable, and make sure any figure you have been quoted is usable rather than gross
Measured State of Health and cell voltage spread
Whether the annual health checks were done, if extended cover is being claimed
Real-world range at current capacity, which on the earlier car is the whole question
Capacity data verified 13 September 2026. Consumption figures marked "modelled" are EV Database estimates rather than physical tests.