The 2026 factors per mile
Government factors for an average-sized company car, kg CO2e per mile, without well-to-tank:
| Car | Scope 1 (fuel) | Scope 2 (charging) | Scope 3 (grid losses) | Total |
|---|---|---|---|---|
| Diesel | 0.27786 | none | none | 0.27786 |
| Petrol | 0.25993 | none | none | 0.25993 |
| Hybrid | 0.20857 | none | none | 0.20857 |
| Plug-in hybrid | 0.14418 | 0.01405 | 0.00139 | 0.15962 |
| Battery electric | none | 0.04322 | 0.00429 | 0.04751 |
The electric factors include charging losses. They also fall each year with the grid: the battery electric car's Scope 2 factor went from 0.05894 in 2025 to 0.04322 in 2026.
A worked example
A firm has 5 average diesel company cars, each doing about 15,000 miles a year. It replaces them with battery electric cars. These are example figures: use your own mileage.
| Fleet | Calculation | tCO2e a year |
|---|---|---|
| 5 diesel cars | 75,000 miles × 0.27786 | 20.84 |
| 5 battery electric cars | 75,000 miles × 0.04751 | 3.56 |
| Saving | 17.28 (83%) |
The 20.84 tonnes of Scope 1 become 3.56 tonnes, mostly Scope 2. For a small firm with a car fleet, company cars can be one of the biggest lines in the footprint, so this can be the largest single cut in a Carbon Reduction Plan.
The carbon payback, honestly
The government's per-mile factors cover running the car only: fuel, or electricity and grid losses. They don't include building it. That matters for the payback question, because building an electric car, and above all its battery, produces more emissions than building a petrol or diesel car.
The best UK evidence is the Lifecycle analysis of UK road vehicles, carried out by Ricardo for the Department for Transport. It found that because the UK's electricity is so clean, a typical battery electric car bought in 2020 was expected to save about 65% of greenhouse gas emissions compared with an equivalent petrol car, over 14 years and 200,000 km, even after the extra manufacturing emissions. It projected that saving rising to about 76% by 2030, as batteries improve and the grid gets cleaner.
So there are two honest answers. In your reported running emissions, the saving starts on the first mile. The car's manufacturing emissions belong in Scope 3 category 2, capital goods, in the year you buy it, if you count that category. Over the car's life, the extra emissions from building it are more than paid back. How quickly depends on the car, the battery size and the miles driven, which is why we don't quote a single payback figure.
What about money?
For employees, company car tax is much lower on an electric car. The appropriate percentage for a zero emission car is 4% for 2026 to 2027 and 5% for 2027 to 2028, then rises by 2 percentage points a year to 9% in 2029 to 2030. Petrol and diesel cars pay much higher percentages, set by their CO2 emissions. Running costs depend on where you charge: our post on counting EV charging explains how to treat home, office and public charging without double counting.
Where to start
- Replace the highest-mileage cars first. The saving is per mile, so a car doing 25,000 miles saves far more than one doing 5,000.
- Use fuel card data for the cars you keep. Litres are more accurate than miles. See our post on company cars and grey fleet.
- Look at journeys too. Some trips don't need a car at all: see train or plane and video calls instead of travel.
How Carbon Recycling helps
Record each company car by size and fuel, by mileage or by fuel card litres, and Carbon Recycling applies the right year's government factors, putting petrol and diesel in Scope 1 and electric charging in Scope 2 with the grid losses in Scope 3. The dashboard's biggest sources chart shows where the fleet sits in your footprint, and you can add the switch to your Carbon Reduction Plan as a planned or completed measure.