By Paul Hollick, commercial director, The Miles Consultancy

Europe’s testing regime for vehicle emissions is under fire – most recently in last month’s autumn statement. But how far removed from real life are its results, and what does that mean for fleets? 

Having looked at real world data on thousands of fleet cars, it is clear that figures from statutory tests are increasingly unhelpful for fleet decision-makers. Of course, the test figures are not intended to be definitive. Everyone expects vehicles to use more fuel in real world driving conditions than they do under lab testing conditions. HMRC adds 15% to manufacturers’ mpg figures when it calculates advisory fuel rates, for example. But when we look at the fuel and mileage data we capture, we often see real world mpgs (and therefore CO2 emissions) that are 30, 40 or even 50% worse.

Fleets see official fuel consumption and CO2 figures that tumble lower and lower each year. But when they use cars in the real world they find that actual mpg has not improved at anything like the same pace.

This reality gap is strongly correlated to official CO2: the lower the official figure, it would appear, the wider the gap. It’s something that affects all manufacturers and all segments, although petrol vehicles generally get closer to their official mpg than diesels.

Because of this phenomenon, more and more of our clients now factor ‘real life costs’, derived from their mileage capture data, into their carbon calculations and wholelife cost projections.

There are many reasons why standard mpg tests will always be off the mark to some extent. But it’s obvious that the current test procedure doesn’t reflect how sensitive today’s low-emission vehicles (especially plug-in hybrids) are to real life variables – particularly driver behaviour.

Reform of the emissions testing regime is overdue. Fleets that are serious about cutting carbon, planning winning strategies and saving running costs now know they can’t simply take official consumption figures and add 10-15%.

In today’s not-as-low-CO2-as-we-thought world, fleets can only rely on the evidence of their own real life data.

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