Average car: carbon footprint per km
Live factor value
0.16591 kgCO2e per km
Source: UK DESNZ greenhouse-gas conversion factors, 2026 (revision 2). Factor set desnz-2026-r2.
The DESNZ 2026 'average car, unknown fuel' factor — shown live below per vehicle-km — is the standard figure for car journeys when you don't know the specific model or fuel. It averages across the UK's petrol, diesel, hybrid and electric fleet.
Driving is most people's largest transport emission source: at typical UK annual mileage the average car produces well over a tonne of CO2e a year. The official tables also publish small/medium/large splits and per-fuel figures, which our travel calculator offers when you know your car's size.
Worked example
Typical UK annual mileage (~10,000 km): 10,000 × 0.16591 = 1,659 kgCO2e.
Measure your own with the free travel calculator.
Frequently asked questions
- What is the carbon footprint of driving per km?
- 0.16591 kgCO2e per km for an average car of unknown fuel in the DESNZ 2026 conversion factors. A small petrol car is lower; a large SUV substantially higher.
- Does the factor cover electric cars?
- The 'unknown fuel' average includes EVs in proportion to the fleet. A pure battery EV charged on UK grid electricity has a much lower per-km footprint — use the car-size and fuel options in the calculator for a closer match.