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Petrol or electric – which is actually greenest?

Volvo makes petrol, hybrid and fully electric versions of the XC40 and has published a like-for-like comparison of lifetime environmental impact

Dan Trent

Words by: Dan Trent

Published on 10 November 2021 | 0 min read

As COP26 focuses our attention on the desperate need to address CO2 emissions what type of car is actually the least harmful to the planet when you compare an internal combustion engined (ICE) option against its battery electric vehicle (BEV) equivalent?
Accepted wisdom has it electric cars are the best compromise for making private transport as green as possible. But an interesting study by Volvo paints a more complex picture, illustrated by the fact its XC40 range offers a genuine like-for-like comparison with ICE, plug-in hybrid and fully electric models all built on shared foundations and in the same factory. Volvo has taken this opportunity to compare the full lifecycle carbon footprint of each type of XC40 from the raw materials and production processes required to manufacture it, fuelling it and driving it over a projected lifespan of 200,000km (or 124,000 miles) and then disposal at the end. Shock news? Building a C40 results in 70 per cent more emissions than making an XC40 with a regular ICE motor, both cars being built on the same platform and sharing many of their parts. In material and component terms alone the batteries account for nearly a third of the footprint of building a C40 or XC40 Recharge.
That means these ‘green’ electric cars actually arrive on your driveway carrying a significant CO2 burden compared with the regular ICE one you could have bought (for a lot less money) instead. The difference comes once you start driving it of course, given every mile you cover in a petrol-powered car burns fuel and adds to its CO2 footprint while the opposite is true in the electric equivalent. The ‘break even’ point where the ICE car’s increasing CO2 footprint overtakes that of the EV and continues to grow depends on where you source the electricity to charge it up again.
Volvo has published three different figures, according to average global electricity supply, the projected ‘EU28’ (the EU, plus the UK) balance of regular and renewable sources and fully renewable energy. Over that 124,000-mile lifespan the fully electric C40’s carbon footprint is 15 per cent less than that of a petrol XC40 and the car needs to have covered 68,300 miles before the break-even point. By the EU28 measure that improves to nearly 30 per cent and 48,000 miles, while if you can charge your C40 purely on renewable energy its lifetime CO2 footprint is half that of the ICE XC40 and break-even comes at just over 30,000 miles.
A similar study by Mazda is the Japanese brand’s reasoning for fitting its all-electric MX-30 with a smaller than usual battery, with the goal of reducing cost and weight while bringing that break-even point forward. That obviously limits range but Mazda reckons the compromise makes sense for an urban-focused product like the MX-30 and will, in time, introduce a range-extender version with an onboard generator for those who need to travel beyond city limits.
So, while it seems over its lifetime a BEV can prove to have a smaller environmental impact than its ICE equivalent, it’s perhaps not as simple as ‘electric cars are greener’ and much of it comes down to the source of the electricity you’re charging it with. For more background on this topic see our ’How green are electric cars’ explainer.