Why does real-world MPG differ from the official figure?

Official MPG figures are measured under standardised laboratory conditions (WLTP in the UK/EU), which are designed for consistent comparison between vehicles — not to predict exactly what you'll get on your daily commute.

Why the gap happens:

• Driving style — steady, gentle acceleration in testing conditions doesn't reflect real-world traffic, hills, or more spirited driving
• Weather and temperature — cold starts, heating, and air conditioning all reduce real-world efficiency in ways lab testing doesn't fully capture
• Payload and load — carrying passengers, luggage, or roof boxes increases weight and drag, both of which reduce MPG
• Road type and conditions — stop-start urban traffic, hills, and wind resistance at motorway speeds all affect real-world consumption differently than the standardised test cycle
• Tyre condition and pressure — under-inflated or worn tyres increase rolling resistance and reduce efficiency

A reasonable expectation:

WLTP figures are more realistic than the older NEDC standard they replaced, but most drivers still see somewhat lower MPG in everyday use, particularly for shorter urban journeys where the engine spends more time working at less efficient low speeds and temperatures. Treating the official figure as a best-case benchmark for comparing cars — rather than a guaranteed number you'll hit day to day — is generally the more realistic way to use it when deciding between models.