Our calculator takes your annual mileage figure and then applies it as follows (assume you drive 10,000 miles a year):
For electric cars: to cover 10,000 miles a year, in an EV with average efficiency of 4 miles per kWh, you need 2,500 units (kWh) of electricity. The maths is: 10,000 divided by 4 = 2,500. Charging at home off-peak at 7p per kWh will cost you £175.00 a year.
For petrol/diesel cars: we assume an average engine efficiency of 39.5 mpg and an average fuel price of £1.39 per litre. To cover the same 10,000 miles, you need 1,151 litres of fuel which will cost you £1,599 per year.