With a temporary shortage of fuel heightening the anxiety levels of combustion engine van drivers, you’d be forgiven for thinking that the woes of an electric driver pale into insignificance. After all, the useable range of an electric van is in some cases more than 200 miles, which, providing there’s regular opportunity to charge, is ample for the majority of use cases. Electric vehicle range anxiety should therefore be reducing for drivers and perhaps as a result the overall experience of driving an electric vehicle is also becoming less stressful.
The big question though is whether an electric vehicle is less stressful to drive than its diesel equivalent, and will electric vans create a new breed of calmer, more relaxed van drivers? With no gear changes, less noise and fewer vibrations, it’s long been hypothesised that EVs deliver a more relaxing drive, but how exactly can you qualify the stress levels of driving an electric van compared to a diesel model?
Using a medical-grade wearable monitor, VanUser took part in an experiment to determine the relative stress levels of driving an electric van, benchmarking it against a diesel equivalent in mid-morning London rush hour. By monitoring the biophysiological responses – that’s to say something akin to the blood, sweat and tears of the driver – a picture can be built up to show a driver’s reactions to the differing sounds of the diesel and electric vans. The vehicles in question were the new Fiat eDucato and the existing and soon to be updated diesel-powered Fiat Ducato.
The device to measure the stress levels was a wristwatch-like gadget called an Empatica E4 that’s not too dissimilar to a wearable health monitor like a FitBit. It uses a photoplethysmography sensor to optically monitor heart rate, electrodermal activity, body temperature and muscle movement. The theory is that an increase in blood flow due to stresses will increase the recorded heart rate and body temperature, while the electrodermal activity measuring the moisture on the skin (i.e. sweat), will rise if the driving becomes more stressful.
Taking matters a step further, an electroencephalograph (EEG) can be used to estimate metrics of brain activity, which can be correlated to show restful or active mental states, which combined with the photoplethysmography sensor can estimate the emotional state of the driver.
In a nutshell, if all the vital signs are elevated, you’re pretty stressed out, and while it might not be solely to do with the acoustics of the vehicle – after all London traffic is renowned for being slightly challenging at times – higher levels across the range of the data, along with a short and snappy stress survey after each drive will help determine the outcome. It’s science then, but with a healthy margin of error, educated guessing and a lot of applied knowledge from psychoacoustic expert Duncan Williams, CTO of biometric and psychoacoustic consultancy firm WaveTrace.
The route for this experiment was through parts of London that will from October 25 fall within the recently expanded Ultra-Low Emissions Zone (ULEZ), making an electric van an ideal candidate for the job – despite still being a relative rarity even in this part of the city – while the diesel van will still be eligible for penalty-free admission by virtue of meeting the Euro-6 emissions targets as well.
Of course, it wouldn’t be a proper experiment with just one test subject, so a total of 12 people took part in the driver stress level comparison, all of whom had varying levels of experience in driving vans, driving in busy cities or neither. In my case, it was very much a question of knowing both vans and not only having experience in busy cities, but also these exact roads, by virtue of having lived not more than a few streets away from the test route. But, to simulate the rigours of a real working day behind the wheel for this otherwise idle journalist, there would of course be a series of package deliveries to perform, requiring not only finding parking, but also some nifty manoeuvring to keep out of the way of people actually going about their proper jobs.
A gambling man would likely predict that the electric vehicle would come out on top in this test for several reasons. The Fiat eDucato’s quick and responsive powertrain makes it well suited to city driving and the lack of a thudding diesel is noticeably more enjoyable – incidentally the diesel engine is nearly 10dB louder than the electric vehicle, the equivalent to four times the volume. However, the test results didn’t show the acoustic impact to be four times greater on my overall stress levels, in fact the diesel van was for this guinea pig moderately less stressful than the electric.
On balance, people reported the EV as being more enjoyable both in their answers to the survey and by a 0.1 point on the perceived stress scale across the test group. The data recorded from the biosensor (the blood and sweat, thankfully without any tears) backed this conclusion up with 4% fewer stress indicators for the EV than the diesel van.
“They certainly didn’t hate the diesel,” Williams said in his report about the test.
Speaking about my individual results, he noted that I reported a total stress scored of -8 for the diesel van and -7 for the EV in the survey, making the EV slightly more stressful, something which was supported by the data from the biomarkers. Looking at the electric van data, Willaims explained: “We can see a huge amount of jagged line in the blue [graph] lots of variation in the electrodermal activity, or sweat.” The diesel the data showed a much more relaxed drive according to the biomarkers.
In truth, it’s far from the outcome I was expecting and while I personally bucked the overall trend of the group by appearing to be more relaxed in the diesel, the margin between the overall group reactions to the diesel and electric Ducato is surprising in its closeness.
Despite the improvement in driving range in many electric vehicles, perhaps we are still subconsciously aware of the range anxiety on some other level, which is hampering our enjoyment of electric driving. Or maybe a myth has actually just been busted, they are no more or less stressful than a diesel, and the argument for enjoying an electric van really does (at this moment in time) only come down to not having to queue up at a forecourt for diesel.