Fuel Cost Calculator - Electric vs Petrol/Diesel - Select Car Leasing
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Fuel Cost Calculator: Electric vs Petrol/Diesel

By leasing an electric car and charging at home, you can save £100s a year on fuel.

Try our handy Fuel Cost Calculator to discover in seconds how much money you can typically save by going electric.

Calculate Your Fuel Savings Below!

By moving the slider, tell us how many miles you drive a year to find out typical annual fuel savings if you switch from petrol/diesel to an all-electric car and charge at home on the capped, government Energy Price Guarantee:

Annual Mileage

I drive 10,000 Miles per year
£978*
Estimated yearly fuel savings in an electric car

Petrol/Diesel*

£1,599
Cost estimate per year
£1.39 / litre
vs

Electric*

£622
Cost estimate per year
24.86p / kWh
vs

Electric with an off peak tariff*

£175
Cost estimate per year
7p / kWh

*Fuel savings and costs are estimated and should be considered as guidelines. The calculations are based on the annual mileage you choose above and the following assumptions: a litre of fuel costs £1.39; your petrol/diesel car has an average efficiency of 39.5 mpg; you charge your electric car at home at 24.86p per kWh (as correct date of: 25/11/2024); your electric car has an average efficiency of 4 miles per kWh.

Want to know more about going electric?

Phone us now on 0118 3048 688 or email one of our expert leasing consultants at enquiries@selectcarleasing.co.uk

Electricity and Fuel Cost Per Mile Analysis

Below are typical fuel costs per mile for EVs and standard petrol and diesel cars. The data is based on a distance of 10,000 miles for cost per mile calculations.

We display both the 24.86p Energy Price Guarantee rate from our calculator above (applied 24 hours a day, if you're on a standard variable tariff), together with an example off-peak home electricity rate of 7p (available at time of writing on 4 May 2023).

The table shows how even greater savings are possible when charging off-peak:


Cost per Mile Vehicle Efficiency Fuel Cost
Electric Car – Off-peak 1.8p 4 miles per kWh 7p per kWh
Electric Car – Energy Price Guarantee 6.2p 4 miles per kWh 24.86p per kWh
Diesel Car 15.0p 43 mpg £1.42 per litre
Petrol Car 17.2p 36 mpg £1.36 per litre

Understanding how much petrol / diesel is per mile illustrates how the electric vs petrol / diesel car comparison favours electric, especially when charging off-peak.

Why Are The Savings So Big?

Our Fuel Cost Calculator summarises how much you can save, on average, when you compare traditional fuel vs electric cars. The secret behind the savings is as follows:

The fuel cost per mile in petrol and diesel cars is high. Why? For two reasons:

  1. Fuel prices at UK pumps are generally quite high – especially at the moment.
  2. Internal combustion engine vehicles are not very efficient at converting fuel into forward motion.

By contrast, the fuel cost per mile in an electric car is low if you charge at home. The main reasons for this are:

  1. Home electricity prices are currently capped at an average of 24.86p per kWh.
  2. Even lower off-peak rates are available if you switch energy provider and/or tariff.
  3. Electric cars – with their batteries and electric motors – are very efficient at using electricity to make the car go forwards.

What Is The Energy Price Guarantee?

The Energy Price Guarantee was brought in by the government on 1st December 2024. It was introduced in order to protect people from very high wholesale gas and electricity prices.

Up to 31 March 2023, for every unit (kWh) of electricity you used at home, your energy provider couldn't charge you more than 24.86p. Both of these capped rates were averages – there were regional differences and you could be charged a little more or a little less, depending on where you live.

From 1 April until 30 June 2023, the average capped rate changed to 24.86p per kWh, down a tiny bit from 34p. 

The Energy Price Guarantee applies to standard variable tariffs. Most of the UK population are now on standard variable tariffs. If you are on a fixed tariff, the way the guarantee applies is more complex. Read the government's Energy Bills Support Factsheet for full details of how the scheme works.

Why Are Fuel Prices So High?

Fuel prices at UK pumps went through the roof last year, though they are stabilising a little now in 2023.

What's going on? The high cost of fuel is mainly down to the following reasons:

  1. The price of crude oil – the raw material that petrol and diesel comes from – has gone up sharply, as supply has failed to keep up with demand, and also in view of serious, ongoing geo-political events.
  2. Oil is paid for in US Dollars, and, as the Pound weakened against the Dollar, it cost us even more in the UK than it did before for the same quantity of oil.

It's also possible that on occasion petrol and diesel retailers may not react very quickly to a decrease in the cost of oil. In other words, the retailer might make a higher profit on a litre of fuel by not passing on a saving in the wholesale price to their customers immediately.

Fuel Cost Calculator FAQs

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.

We use the average of the latest diesel cost per litre and petrol cost per litre nationwide (fuel data sourced from the RAC).

We update our fuel cost calculator at least every month with the latest fuel prices.

For the standard rate in the main calculator, we use the official government-backed Energy Price Guarantee rate of 33.2p per kWh. A protected rate has been in force since 1st October 2022 and applies to all standard variable home electricity tariffs.

For the off-peak rate in the calculator, we use an actual rate from one of the leading dual rate tariff providers in the UK.

Some public charging points are free to use. For example, certain supermarkets allow you to charge for free while you shop.

However, to use the more advanced, faster public chargers – known as ‘rapid’ chargers – you nearly always have to pay. Rates typically vary from about 24.86p per kWh to as much as 80p per kWh or more.

If you only use rapid chargers occasionally, you will still save a lot of money by switching to electric motoring.

If you do most of your charging at rapid charging stations, then your savings will be much less and it might even be cheaper in a petrol or diesel car, depending on what kWh rate you pay.

Yes, we update all the fuel and electricity price assumptions once a month at the latest. The Fuel Cost Calculator should therefore give you a fairly accurate average savings result, though regional and supplier differences will change the result in specific situations.

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