2011 marked the introduction of a new generation of refined and reliable EVs into the UK from mainstream automotive manufacturers. Combined with UK government grants for both car and van purchase and the creation of charging infrastructure, the momentum for plug-in vehicles will continue to grow as a range of new models are set for release.

Recognising the potential for growth in EV adoption, we recently published a study that looked at the feasibility of integrating small passenger car EVs into fleets, and surveyed the perceptions of fleet drivers and managers. The study reported on a Cenex trial incorporating EVs into fleets across the UK; including Asda, Indesit and Stagecoach.

The study findings revealed that relying on the nameplate range of an EV proved problematic when planning vehicle duties in advance of any EV experience, as the real-world range was shown to be lower than the published figure might otherwise indicate, due to factors including driving duty and driving style, as well as the winter use of in-cab heating drawing energy from the battery pack.

However, the case studies also showed that when EVs are incorporated into environments with an effective and well executed ‘opportunity charging' policy, they are capable of achieving significant improvements in range compared to a single overnight vehicle charge. The increased range arises from being able to utilise over 100% of battery state of charge (SoC) per day. This was demonstrated by Stagecoach, where 26% of their daily deployments (transferring bus drivers and ticket inspectors) used over 100% SoC and the highest daily SoC used was 160%.

Battery operation ensures strong environmental credentials in terms of zero tailpipe emissions and low noise emissions. In the case of CO₂ on a well-to-wheel basis, CO₂ reductions of up to 15% were shown to be available from EV operation when compared with the equivalent diesels, which in the study case were the best-in-class smart Cdi, with regulated emissions of just 86 gCO₂/km.

The downside of ‘opportunity charging' is that it means charging vehicles during daytime hours whereas off-peak charging is lower cost and typically better for low CO₂ emissions. Studies have shown smart charge units (i.e. tariff or timer signal responsive) to be an effective method of redistributing EV charging times, allowing a significant increase in off-peak charging. However, such units were not available to the organisations participating in this trial which led to just 12% of charging using cheap rate night time electricity. In a well planned deployment for return-to-base and home-charged vehicles, smart charge units would be recommended to improve the economic and environmental performance of the vehicles.

Questionnaire results for individual users showed enthusiasm for the EVs. On average, users rated the performance aspects of EVs as marginally better than conventional vehicles and 75% stated they would be happy to change their working procedures to incorporate EVs. Fleet managers also displayed very positive attitudes towards the EVs and 75% said their opinion of EVs improved over the trial thus proving the value of the real-world vehicle experience provided by participation in the project.

The findings of this trial show that modern EVs are of sufficient quality and reliability to be accepted by both managers and their staff. Although there are still challenges in terms of economic performance and range, these can be overcome by introducing EVs into appropriate duty cycles.

At Cenex, a duty cycle approach to total cost of ownership modelling is used where a fleet is characterised and EV vehicle performance is simulated over the fleets' different duties to identify the ‘sweet –spots' within fleet operations. In this way, cash and carbon savings can be realised without compromising fleet operability...even in winter!