Earlier this year, discrepancies of between 30% and 40% against the official combined economy figures were also measured on three cars powered by a 118bhp 1.6 BlueHDi diesel, namely a Peugeot 308, Citroën C4 Grand Picasso 1.6 and DS 3. For example, the 308 recorded 56mpg compared to a customer figure of 55mpg and the EU combined test figure of 88mpg.
Peugeot's says its new real-world tests use a 96km (59.7-mile) route that is made up of a mixture of urban, country and motorway routes. It uses a selection of professional and amateur drivers, not directly employed by Peugeot, to ensure the results are as accurate as possible.
The test procedure has been conceived in conjunction with three non-governmental organisations: Transport and Environment, France Nature Environment and Bureau Veritas.
“We have come up with a very strong vision that will give full transparency for our customers,” said PSA Group chairman Carlos Tavares. “This new test cycle will be much more representative of a consumer’s real driving experience.
“VW-gate has created a lot of concern in our company - we are the industry leaders on fuel efficiency and diesel emissions, so if there is an action that breaks the trust of buyers it is a big concern.
“We want to demonstrate openness and confidence. We do not want to be confused with our German competitors on this issue, and the real-world tests are one way of demonstrating that.”
PSA maintains that the test is repeatable and reliable, even though key factors like the wind, temperature and driving style are not under control in the way that they are in a laboratory. The cold start part of the test, during which fuel consumption is heavy, is ‘factored’ into the result and on-road tests won’t be carried out if the wind is above a certain speed.
The test can be monitored by GPS and if the driving style or traffic fall outside acceptable limits, the test will be cancelled. Tests are monitored by Bureau Veritas, a consultancy firm that specialises in inspection and certification.
Pierre-Yves Etienney, Peugeot's small cars PR boss added: "We intend to eventually test our entire range and publish the figures, helping people make a more informed choice. The next set of figures will be published around July.
"We are the first to be doing this sort of testing, and that's great, but we hope other manufacturers will follow us."
Transport and Environment is the green lobby group that was involved in exposing the Volkswagen dieselgate scandal and its boss Greg Archer helped devise the new test. T&E says it has not been paid for the work.
“We have had some differences on methodology with PSA, but we believe that this new test is a very good correlation to the real world,” said Archer.
PSA will also use the test to produce real-world economy figures that will become a legal requirement under the new worldwide harmonised light vehicle test procedure (WLTP), in force from September 2017.
According to T&E, PSA’s test will also show a discrepancy of 20% with the WLTP combined economy.
Additional reporting by Sam Sheehan