Below are some details on how to use the Journey Cost Calculator and the assumptions made when calculating your journey costs.
Selecting your vehicle
On the first screen you need to select your vehicles for comparison. Firstly choose a pure electric vehicles or plug-in vehicle, the default shows you new cars that are available to buy now, but you can also select the Used button to find any plug-in car which has been on sale in the UK. Next select your comparison vehicle, this can be another plug-in vehicle or a petrol / diesel car.
Adding your journey details
On the input screen you are asked to provide details about your journey distance - you can either enter a mileage value or, using the Plan a route option, enter the start and destination of a typical journey and the tool will calculate the distance. The default journey frequency is daily, but you can change to monthly or annually as desired.
The home electricity cost, which will be used to calculate your electricity costs, defaults to the UK average. Source: UK Government - updated annually. You can edit and change to your own tariff if you wish.
If you have chosen a petrol, diesel, hybrid or plug-in hybrid you will also be able to change the default cost per litre. The default shows the UK average from petrol prices Petrol Prices and is updated monthly.
Your journey cost results
Your journey costs using the two vehicles selected are calculated using the vehicle, distance and fuel price data selected or entered via the mapping tool. The results are displayed in three ways together with a cost comparison over a year:
- Journey fuel costs = fuel economy x miles x fuel price. Results are rounded to the nearest whole £pound.
- Cost per mile = fuel economy x fuel price. Results expressed in pence per mile.
- Total annual fuel costs = fuel economy x miles x fuel price x journeys per year. Results are rounded to the nearest whole £pound.
More details on fuel economy calculations by vehicle type
A vehicle's fuel cost is calculated by multiplying its fuel economy (using units of litres or kWh per 100 km) by fuel price (in pence per litre or kWh) and the distance driven (in kilometres). Inputs and results are shown in imperial units (miles-per-gallon, pence per mile and miles) using appropriate conversion factors.
The calculator, which can be used for all vehicle types (petrol, diesel and plug-in vehicles), provides results based on official NEDC data only.
For vehicles powered solely by electricity, fuel cost is calculated by multiplying the fuel economy (in kWh per 100 km) by fuel price (in pence per kWh) and the distance driven (in kilometres or miles). The real-world electric cost is calculated using real-world driving tests, or where not available, estimated from official NEDC test figures for fuel economy.
Plug-in hybrid vehicles
For plug-in hybrid vehicles powered by electricity and petrol or diesel, fuel cost for both fuels is calculated multiplying the fuel economy (in litres and kWh per 100 km) by fuel price (in pence per litre and kWh) and the distance driven (in kilometres or miles). The fuel cost is estimated using the assumption that the vehicle is driven for half the distance in electric-only mode and half using a conventional fuel ('Condition B'); Real-world figures are used for both figures.
Petrol and Diesel vehicles
For vehicles solely powered by petrol or diesel, fuel cost is calculated by multiplying the fuel economy (in litres per 100 km) by fuel price (in pence per litre) and the distance driven (in kilometres or miles). The real-world fuel cost is from real-world driving tests or where not available estimated from test-derived figures ('official combined') for fuel economy as published by the NEDC.
The data and calculations behind these tools is provided by Next Green Car Ltd and subject to the Terms and Conditions of use