Car methodology
DEFRA
UK Government conversion factors
UK Government factors per kilometre by car size and fuel, from the conversion factors for company reporting. Use them when the exact car is unknown.
- Publisher
- UK Government (DESNZ)
- Best for
- UK-based reporting and cars of unknown model
- Result
- One total per car trip
- Energy scope
- WTW by default, TTW optional
- Factor year
- Selectable; latest supported year by default
How it works
- The size class can come from the rental code on the booking.
- Factors for electric and plug-in hybrid cars use UK grid electricity.
- By default the result includes producing and delivering the fuel or electricity.
Trip details used
When a detail is missing, SQUAKE uses the default.
| Detail | Default | Notes |
|---|---|---|
| Distance driven | From the route or rental days | Measured kilometres give the best result. |
| Start and end locations | None | Used to calculate the distance. |
| Rental days | None | Fallback only: 60 km per day. |
| Car size | Average | From mini to luxury, plus sports, 4x4 and MPV. Can come from a rental code. |
| Fuel | Average | Petrol, diesel, hybrid, plug-in hybrid, electric or gas. |
What is included
Included
- Burning the fuel, or for electric cars the UK grid electricity used
- Producing and delivering the fuel or electricity (on by default)
Not included
- Vehicle manufacture, maintenance and disposal
Limitations
- Averages by car size and fuel, not a specific make or model.
- Based on UK fleet and grid averages.
Sources
- UK Government: conversion factors for company reportinggov.uk
Every annual factor set, with its methodology paper.