A lower range estimate on a cold morning is a reason to plan carefully, not a battery-health measurement. Keep three observations separate: the dashboard estimate, the distance actually driven and any formal battery assessment.
UK electric MG owners comparing ordinary journeys. This is an evidence worksheet, not a diagnostic battery test or a promise of a particular winter range.
01 / Compare like with like
MG UK's current MG4 EV Urban page states that test range may differ from actual driving, including the effects of weather, driving style, load and accessories. That principle is a useful reason to record conditions; the Urban's specification is not a substitute for another MG's figures. A motorway trip with heating, rain and a cold start is a different comparison from a mild, slower journey.
Record the exact car, starting and ending charge, miles travelled, outside temperature, main road type, climate use and unusual load. A single reading after a short trip can be dominated by warm-up and cabin heating. Look for a repeatable pattern across normal use.
02 / Make one useful calculation
Consumption example — not an MG specification
If the vehicle reports 40 kWh used over 160 miles, the arithmetic is 160 ÷ 40 = 4 miles/kWh. Compare that figure with similar journeys in the same car and conditions.
A charger receipt showing 40 kWh delivered does not mean 40 kWh was used for that journey: charging losses, battery temperature and a different start/end charge matter. Do not mix those measurements.
If you only know miles and the percentage drop, keep them as observations. Turning them into a precise usable battery capacity assumes too much about the displayed percentages and energy used elsewhere.
03 / Use the tools within their scope
Range planning explores assumptions before a trip. Range Twin learns from records you choose to enter for a supported exact current UK grade. Neither reads the car, guarantees arrival energy or certifies battery health.
For an older MG not represented in a selector, do not choose a newer car with a convenient-looking battery number. Keep your actual figures in a dated note and use the appropriate original vehicle documentation.
04 / Know what deserves investigation
If a large change repeats under comparable conditions, preserve the journey records, full warning messages and relevant charging logs for a qualified assessment. Ask what a quoted “state of health” percentage measures and request the dated report behind it. Do not infer a fault or a warranty outcome from a dashboard range number or a forum screenshot.
Do not drive towards empty to prove a range claim. Keep a practical reserve and alternative charging options. If the car displays a safety or stop warning, follow that warning instead of continuing a range experiment. The existing winter range and charging guide covers the broader cold-weather checks.
Evidence and limits
Reviewed 16 October 2026. Manufacturer background: MG UK: MG4 EV Urban, range and charging caveats. The worksheet and numerical example are original editorial guidance. UK owner discussions informed the question; their mileage reports are not presented as representative data or proof of battery degradation.