What does “CO₂ saved” mean?

It’s an estimate of the tailpipe CO₂ emissions avoided when you choose to drive an electric vehicle (EV) instead of a petrol/diesel car for the same route.

How do you calculate it today?

We take the route distance shown in Journey Planning.We apply an ICE tailpipe emissions factor (grams of CO₂ per kilometre).We assume EV tailpipe CO₂ = 0 (no exhaust emissions while driving).In simple terms: ICE tailpipe CO₂ (kg) = (ICE gCO₂/km × distance km) ÷ 1,000 EV tailpipe CO₂ (kg) = 0CO₂ saved (kg) = ICE tailpipe CO₂ − EV tailpipe CO₂

Where does the emissions factor come from?

If you’ve added a vehicle in ‘My Garage’, we aim to use the best available emissions value for that vehicle type.If we don’t know your exact vehicle, we use a reasonable default based on recognised UK reporting guidance and clearly treat it as an estimate.

Does this include the electricity used to charge my EV?

Today, the “CO₂ saved” value focuses on tailpipe emissions avoided only.
In future releases, we plan to extend this towards a fuller “well-to-wheel” view (including electricity generation and other factors) and support public transport and micro mobility legs.

Why might the estimate differ from real life?

Because real-world emissions vary with:Traffic, speed, weather, elevation, vehicle load, driving styleThe exact vehicle model/condition (especially if unknown and we use defaults)Route changes and detoursWe aim to be as accurate as possible, but this figure should be treated as an informative estimate, not an exact measurement.

Which standards or guidance do you follow?

We align our approach with the transparency principles of ISO 14083:2023 (clear scope, assumptions, and data sources). For emissions factors, we reference recognised UK reporting sources such as the UK Government’s GHG Conversion Factors.

What’s coming next?

As we introduce public transport and micromobility, we’ll expand the calculation to support multi-modal journeys and provide clearer breakdowns by leg (e.g., walk → bike → train).

References (for users who want to read more)

ISO 14083:2023 (standard page)
ISO 14083:2023 UK Government conversion factors (collection)
Government conversion factors for company reporting of greenhouse gas emissions UK Government conversion factors (2025 publication)
Greenhouse gas reporting: conversion factors 2025