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Real-world mpg figures would allow true cost comparisons

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The fleet industry is calling for more manufacturers to follow PSA Group’s lead and publish real-world fuel economy figures.

The French manufacturer announced the bold step to publish real-world data for Peugeot, Citroën and DS models last November, in the wake of the Volkswagen Group emissions scandal.

However, with most fleet operators basing vehicle choice on wholelife cost calculations (WLC), which includes fuel, fleets are unable to do accurate like-for-like comparisons between PSA vehicles and other cars or vans.

Caroline Sandall, deputy chairman of fleet representative body ACFO, told Fleet News: “Doing any comparison, you need to compare like with like so real-world versus standard published won’t be like-for-like.

“We already know from other tests that standard published data can vary significantly, so including fuel and mpg is already fraught with difficulty.

“We need this real-world data to be replicated across all models and all manufacturers so that true comparison of WLC can be made and drivers can make more informed decisions when selecting their next car.”

The PSA Group issued its first real-world consumption figures for three models – one each for its three brands – at the Geneva Motor Show in March and has since added a fourth model.

The real-world test procedure, based on the European Union’s real driving emissions (RDE) project, was conducted with Transport and Environment, France Nature Environment and Bureau Veritas.

It showed discrepancies of between 30% and 40% against the official combined figures on the Peugeot 308 and 2008, Citroën C4 Grand Picasso and DS3 powered by an 118hp 1.6-litre Blue HDi diesel. It has also tested the 99hp engine on the 2008 with similar results.

The PSA Group says that some 30 models should be available with real-world data by the end of this month.

“The test developed with PSA Peugeot Citroën is reproducible and representative,” said Greg Archer, clean vehicles director at campaign group Transport & Environment.

“This should become the benchmark for all carmakers advertising their vehicle’s fuel efficiency.”

Real-world fuel economy figures will become a legal requirement under the new worldwide harmonised light vehicle test procedure (WLTP), which is due to come into force from September 2017.

Until then, companies will be left facing a dilemma when trying to compare the ‘true cost’ of cars before allowing them on choice lists.

Claire Evans, head of consultancy at Zenith, said: “Assessing the true WLC of a vehicle has always proved tricky for fleets that reimburse their drivers using the actual cost of fuel.

“It is common knowledge that the accuracy of miles per gallon can vary greatly depending on the make and model of the vehicle, and the usage and handling style of the driver.

“Electric-hybrid vehicles are even more difficult to predict as the mpg achieved is completely in the hands of each driver and their diligence in charging the car.”

In Zenith’s experience, fleets already tend to assume that vehicles will achieve an average of 15-20% less than the published combined mpg figure.

“We suggest that fleets use the fuel cost calculated from this reduced mpg position to compare with the real-world fuel economy of the PSA models until other manufacturers follow suit and publish more realistic mpgs for their cars,” continued Evans.

“There is, however, a drawback to using this flat rate reduction approach, as the disparity on real-world to published mpg figures can vary greatly with some sources quoting a difference of between 10-40% depending on the make and model of the car.”

As with all fleet decision-making, having accurate information to calculate the running costs of a vehicle is crucial for fleet managers. Fuel is the second largest fleet cost and fleets will welcome any move which helps them better understand the true WLC of their fleet.

“They hope this starts a trend for manufactures to be more proactive about providing honest real-world mpg figures,” said Evans.

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  • Bill - 17/06/2016 12:18

    Fuelly.com is a great resource for finding out how models perform in the real world. Obviously, it relies on accuracy from its users, but I doubt most people have little to gain from skewing the figures.

  • Robberg - 17/06/2016 13:51

    Real world figures will be just as variable as laboratory figures. What is real world driving? A steady speed on the motorway or chugging around town? I've always used the laboratory figures only as a benchmark between cars.

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