EV vs Petrol Which is Cheaper: The Method, a Worked Example, and the Factors That Matter

There is a lot of confident advice about ev vs petrol which is cheaper and much of it is wrong in the details, usually because it leaves out the conditions the answer depends on. This page works through the question properly: what it is, why it matters, how to do or check it, and the mistakes that catch people out.

For ev vs petrol which is cheaper, the point is this: Below you will find the explanation, a worked example with the assumptions stated, a table where one helps, and the factors that push the result up or down. Read the whole page before you act, because the step that matters most is often the one people skip.

What you need to know first — ev vs petrol which is cheaper

For ev vs petrol which is cheaper, the point is this: What the energy comparison leaves out matters as much as what it includes. Purchase price, depreciation, insurance, servicing and tax are not in the fuel-and-charging maths, and they differ between an EV and a petrol car. Battery degradation is part of the same picture: batteries lose capacity slowly with age and use, and that affects range over the years, though how fast depends on the battery, the charging habits and the climate. A full comparison names everything it excludes rather than hiding it.

What makes ev vs petrol which is cheaper worth understanding properly is that a small error at the start — a wrong figure, a skipped check — grows into a large error by the end, and the cost of that error is paid in tyres, fuel or safety.

How it works in practice — ev vs petrol which is cheaper

On this page, ev vs petrol which is cheaper is the case in point: Comparing an electric car with a petrol car on running costs comes down to the price of energy per mile, and the two sides are worked out differently. A petrol car's cost per mile is the fuel price divided by its MPG; an EV's cost per mile is the electricity price divided by its miles per kilowatt-hour. The comparison only works if both sides use the same annual mileage and honest, stated assumptions, because the electricity price depends on where and when the car is charged, and the petrol price depends on the pump.

Worked example — ev vs petrol which is cheaper

On this page, ev vs petrol which is cheaper is the case in point: Take a driver covering 10,000 miles a year as an example figure. The method on this page works the same at any mileage, so the example is there to show the arithmetic, not to state a fact about your car. Start with the measurement or the figure you can check yourself — a gauge reading, a tread-depth reading, or the figure on the placard — and write it down before you do anything else. Then apply the method step by step, checking each result against the one before it, because an error early in the chain is the one that is hardest to spot later. If the result surprises you, check the inputs first: a pressure read on warm tyres, a tread depth measured in one spot only, or a figure taken from the fitted tyre instead of the placard will each give a wrong answer that looks plausible. That is why the worked example on this page states its assumptions openly, and why you should do the same with your own figures.

What changes the answer — ev vs petrol which is cheaper

On this page, ev vs petrol which is cheaper is the case in point: Charging is where the answer moves most. Home charging overnight is usually the cheapest electricity a driver will buy, while public rapid charging can cost several times as much per kilowatt-hour, so a driver who charges mostly at home and a driver who relies on rapid chargers can reach opposite conclusions about the same car. The honest method is to work out your own mix — what share of charging is at home, what share is public — and price each part separately.

  • Taking ev vs petrol which is cheaper as the case in point: Electricity price: home charging is usually cheapest, public rapid charging is usually dearest.
  • Petrol price: the pump price you actually pay, labelled as an example when used in a worked calculation. That is the point this page works through for ev vs petrol which is cheaper.
  • Efficiency: miles per kilowatt-hour for the EV, MPG for the petrol car, both measured in real driving. That is the point this page works through for ev vs petrol which is cheaper.
  • For ev vs petrol which is cheaper, the point is this: Mileage: the saving per mile grows with the miles driven, so high-mileage drivers see the biggest difference.
  • For ev vs petrol which is cheaper, the point is this: Battery: capacity falls slowly with age and use, which affects range over the years.
  • On this page, ev vs petrol which is cheaper is the case in point: Servicing: EVs have fewer moving parts to service, but tyres and brakes still wear and need attention.

Common mistakes — ev vs petrol which is cheaper

  • For ev vs petrol which is cheaper, the point is this: Comparing an EV charged at home with a petrol car on the most expensive fuel, or the reverse, instead of using honest figures for both.
  • For ev vs petrol which is cheaper, the point is this: Forgetting the charging mix and pricing every kilowatt-hour at the home rate.
  • Leaving purchase price, depreciation, insurance and servicing out of a total-cost claim. That is the point this page works through for ev vs petrol which is cheaper.
  • On this page, ev vs petrol which is cheaper is the case in point: Treating a laboratory efficiency figure as the real-world figure for either car.

Step by step — ev vs petrol which is cheaper

  1. For ev vs petrol which is cheaper, the point is this: Write down your annual mileage, because every part of the comparison divides by it.
  2. On this page, ev vs petrol which is cheaper is the case in point: Find the electricity price you actually pay at home and the price of the public charging you use.
  3. Taking ev vs petrol which is cheaper as the case in point: Work out the EV's cost per mile by dividing the electricity price by the miles per kilowatt-hour.
  4. For ev vs petrol which is cheaper, the point is this: Work out the petrol car's cost per mile by dividing the fuel price by its MPG.
  5. On this page, ev vs petrol which is cheaper is the case in point: Multiply each by your annual miles and compare, noting the charging mix you assumed.
  6. On this page, ev vs petrol which is cheaper is the case in point: List what is excluded — purchase price, depreciation, insurance, servicing and tax — before drawing a conclusion.

What can go wrong, and when to see a professional — ev vs petrol which is cheaper

Most problems with ev vs petrol which is cheaper announce themselves early if you know what to look for: uneven wear, a vibration that was not there before, a warning light, a noise that changes with speed, or a reading that does not match the placard. None of these is a reason to panic, and all of them are reasons to check the basics first — pressures with a gauge when the tyres are cold, tread depth across the whole tread, and the figures on the placard rather than the ones on the fitted tyre. If the basics are right and the symptom is still there, or if you find a bulge, a deep cut, a cracked sidewall or a tyre that is losing pressure quickly, that is the point to see a tyre professional rather than to keep driving and hoping. A professional can see the inside of a tyre, measure the alignment angles and test the sensors, and those are the checks that cannot be done from the driveway. The cost of an inspection is small beside the cost of a tyre worn out early or a problem found too late.

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Frequently asked questions

How much does it cost to charge an EV at home?

For ev vs petrol which is cheaper, it depends on the electricity price you pay and the size of the battery. Multiply the price per kilowatt-hour by the kilowatt-hours needed for a full charge, or divide the price per kilowatt-hour by the car's miles per kilowatt-hour for the cost per mile. Off-peak tariffs can make home charging much cheaper than charging during the day.

How long does it take to charge an EV?

For ev vs petrol which is cheaper, it depends on the battery size, the charger's power and the starting charge level. Home charging is slowest and usually done overnight; public rapid charging is fastest but dearest. Charging from 10 to 80 percent is much quicker than charging to 100 percent, because the rate slows as the battery fills.

Do EV batteries degrade, and does it matter?

For ev vs petrol which is cheaper, yes, batteries lose capacity slowly with age and use, which reduces the range over the years. How fast depends on the battery, the charging habits and the climate — frequent rapid charging and high temperatures tend to speed it up. The effect is gradual, and the car's range figure should be checked over time rather than assumed.

Do electric cars wear tyres faster?

For ev vs petrol which is cheaper, they can do, because EVs are often heavier than similar petrol cars and deliver strong torque from a standstill, both of which wear tyres faster. Gentle acceleration and correct pressures help. The difference is a running-cost factor worth counting, and it belongs in the tyre cost per mile for the car.

Is an electric car cheaper to run than a petrol car?

For ev vs petrol which is cheaper, on fuel and charging alone, usually, when the EV charges mostly at home — but the answer depends on the electricity price, the petrol price and the mileage. A driver who relies on expensive public rapid charging may see little saving. Purchase price, depreciation, insurance and servicing are not in the energy maths, so a total-cost comparison has to include them.