Everyone who drives an EV will have had the conversation. Someone asks what it’s like, you tell them it’s great, they ask how much it costs to run, and you say something vague like “hardly anything compared to petrol.” Which is true. But it’s not an answer.
I’ve been in that conversation more times than I can count, and the honest truth is that most EV drivers — myself included, for a while — don’t actually know their real numbers. They know it’s cheaper. They’ve got a rough sense of what they’re spending. But the actual pence per mile, the real-world MPG equivalent, what they’d save over a year compared to a petrol driver doing the same mileage? Most people have never sat down and worked it out properly.
That’s what the EV MPG Calculator is for.
It’s something I’ve wanted to build for a while, partly because I think EV drivers deserve a clearer picture of what their car is actually doing, and partly because the numbers — when you do work them out — are genuinely staggering. My Volvo EX30, on home charging at 7.5p per kWh and returning 4 miles per kWh, is costing me under 2p a mile. The petrol equivalent of that, at today’s prices, is somewhere north of 370 MPG. That’s not a figure you can explain in a conversation at the pub — but it’s one you can show someone on a screen.
The calculator takes your real-world figures — the miles you’ve actually driven, the kWh you’ve actually used, what you’re actually paying per kWh — and turns them into something meaningful. It’ll show you your true pence per mile, what that works out to in MPG terms so you can compare it to any petrol or diesel car, and how much you’d save over 8,000 miles against a car of your choice. You can also run it on a car you’re thinking about buying, using the manufacturer’s claimed range and battery capacity, which at least gives you a starting point before you sign anything.
You can also use the manufacturers’ claimed figures to help work out an EVs running costs.
One thing I’d really encourage people to pay attention to when they use it is the cost per kWh they enter. It makes a bigger difference to the results than almost anything else. Home charging on a decent overnight tariff is where the real savings are — and some of the EV-specific energy tariffs available now are so much cheaper than public rapid charging that it almost doesn’t feel like the same activity. If you’re regularly using public chargers because you haven’t sorted a home setup yet, or because you haven’t looked at your tariff recently, the calculator will make that very obvious very quickly.
If you’re looking to compare with a petrol/diesel car and don’t know the MPG. It would be safe(ish) to assume a petrol would return about 30MPG and a diesel 45MPG.
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If you’d like to read more about what efficiency metric I prefer to use in my EV, then check out the article below.
