Real-world fuel economy tests on light commercial vehicles have shown an average 17.1% reduction on official figures.
The data comes from Emissions Analytics, which says it’s seen similar levels of variability from official fuel economy and emissions figures in vans as in cars, with real-world van economy varying from -5.3% to -38.8% on official figures. However it adds that the mpg gap is smaller than for passenger cars which was 29% in 2016, perhaps because light commercial vehicles are not being hyper-optimised to the NEDC.
As with cars, all of these vehicles were homologated to either the Euro 5 or Euro 6 standard – the results show there are seven Euro 5s and three Euro 6 vehicles which have been rated ‘H’ on the EQUA Aq Index, meaning they emit 12 times or more the current Euro 6 limit when they are out of laboratory conditions.
The best performing diesel van in the Emissions Analytics tests was the Euro 6 VW Transporter, scoring an B-rating on-the-road, meaning it is just 1.5 times the legal limit. This is mirrored in the passenger cars tested, where only 15 of the 131 Euro 6 diesel cars tested meet the standard, of which 10 are from the Volkswagen group.
Emissions Analytics also ran tests to find out the effects of load on fuel economy. Tested on the same EQUA cycle as passenger cars, vans additionally ran parts of the route ballasted to 50% of their maximum payload. The effect of load on fuel economy is an average of -11.2% for a fully loaded van.
Based on an average diesel price of 122.12p/l), the firm says this shows that for every 100 miles driven with a fully loaded van, refuelling costs on average £1.91 more than empty, equating to approximately £450 per year based on DfT mileage figures.