It is well known that carrying unnecessary weight in a vehicle increases its fuel consumption. However, by how much has been debated for some time.

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>In May 2010 AEA undertook research that measured the fuel consumption for a number of vans over the NEDC test cycle while fully ladenand empty. The results of this research indicated that the average increase in fuel consumption when fully laden was around 8%, even though the load typically added around 50% to the total vehicle weight.

It therefore seems reasonable to conclude that the amount of weight most of your drivers might unnecessarily carry in their vehicles would only have a small impact on fuel consumption.

However, the NEDC cycle contains gentle acceleration and in duty cycles with more stop-start and faster acceleration we would expect weight to have a bigger impact.

It was for this reason that Cenex undertook new research, which for the first time modelled the impact of weight on fuel consumption using real-world driving conditions. This research was carried out on behalf of the Energy Saving Trust, which was keen to utilise Cenex's unique experience in modelling vehicles over real world drive cycles to ascertain the real impact.

For this research we used our in-house fleet carbon reduction tool, a sophisticated vehicle simulation and modelling software package, to help identify the potential fuel consumption benefits of reducing weight within a panel van and car-derived van. The research compared these vehiclesempty and fully loaded on typical urban and rural driving routes (using the Artemis Urban and Artemis Road drive cycles respectively), which more accurately represent realistic driving conditions.

Under urban driving conditions our analysis found that a typical car-derived van, such as a Volkswagen Caddy, would use around 26% less fuel when empty compared to when fully loaded. A fuel saving of around 5% was achievable with a weight reduction of 150kg.

As for panel vans such as the Peugeot Boxer, the difference in fuel consumption was up to 33%, with 3% fuel savings achievable with a weight reduction of 150kg.

It is accepted that not everyone can reduce their weight by 150kg; however we have estimated that if half the van drivers in the UK lightened their loads by 75kg ' equivalent to three bags of cement or an empty industrial gas cylinder ' they could save a total of around £50 million on fuel each year.

This would also result in around 100,000 fewer tonnes of carbon dioxide emissions being released.

How many of your drivers treat their van as a mobile store room for rarely needed equipment or parts? Reducing the amount of additional weight in your vans will not only improve their fuel economy but could also reveal that the vans are bigger than necessary, with underutilised space.As a result, you could consider downsizing and opting for smaller, more economical vans which better suit your operational needs.