Professional Engineering

These days our lives are full of “too good to be true” offers. Our inboxes overflow with £1 million deals with Nigerian princes and we win loads of competitions that we never remember entering. These scams appear to have become an accepted part of life, and victims blame themselves rather than the perpetrator if they fall for the trick. 

Now it seems that the scam culture has traversed to mainstream car advertising with the advent of “zero emission” vehicles. 

Sorry, but powering a car with electricity does not make it “zero emission”. The caption in tiny letters might explain that “tailpipe” emissions are referred to but how is the public really expected to interpret this statement? Generous observers would call it marketing spin, but to me it is just another scam.

The truth is that electric cars use electricity from the national grid. Using the Nissan Leaf electric car as an example, the maker’s quoted figures equate to about 72g of CO₂ emissions from a power station for every kilometre driven. To be fair, this is a good result – lower emissions than from even the eco versions of regular internal combustion engined cars. But zero? Not even close.  

So what about the government’s preferred terminology of ultra-low carbon vehicles? Well, I don’t think this is much less of a scam either. 

When we switched to low-sulphur diesel, sulphur content was limited to 50ppm so the following ultra-low sulphur diesel at 10ppm or less seems aptly named. If a low-carbon vehicle is sub-100g/km (the threshold for free road tax) we might reasonably imply that ultra-low carbon vehicles emit less than 20g/km, which they clearly don’t. 

It seems that because electric vehicles emit their CO₂ while being charged instead of while driving and because legislation is centred around tailpipe emissions this sort of misleading language has come to the fore. But most of the public don’t understand the nuances of the NEDC emissions test. They don’t understand that range-extended electric vehicles do the test twice, once in all-electric mode and once in petrol-engined mode. The quoted figure for CO₂ emissions is a weighted average that takes into account the maximum range of the vehicle on pure electric while only counting CO₂ from the petrol. 

So many people expect that if they make the green choice and buy a Vauxhall Ampera with official emissions of 40g/km it really emits only this much when they drive. Unfortunately it emits more than double this if you account properly for the electricity. And, depending on your journey, emissions may well be higher than those of a conventional internal combustion engined car. 

The latest TV advert for the Ampera promises 360 miles on electricity – yeah, right! More like 50 miles on electricity and 310 miles at 47mpg on petrol. 

We should also be concerned that the amount of CO₂ released during the manufacture of electric cars is higher than that for conventional vehicles. It used to be that “embedded” CO₂ was a small proportion of the in-use emissions, but as in-use emissions fall and manufacturing emissions go up there is now a strong case for cradle-to-grave measurement. 

Please don’t get the impression that I am anti-electric vehicles. I am strongly in favour of anything that genuinely lowers CO₂ emissions and I do think that electric vehicles have a place in helping to do this. 

But describing these vehicles using terminology that is so misleading raises the anti-scam alarm in us all and is positively harmful to the cause.