What Car?’s True MPG testing has revealed that new official fuel economy tests are providing more accurate results than ever before, but still an average of 4.9% worse than claimed.
This is far better than the 23.5% average shortfall for cars tested before the new regulations came into effect but highlights the fact that consumers should remain wary of taking official figures for granted.
What Car? compared the real-world economy figures achieved under its True MPG real-world test against official recorded figures recorded using the new, tougher WLTP tests.
In a 15-vehicle sample, What Car? found the manufacturer quoted economy figures were, on average, 4.9%, or 2.6mpg, higher than its testers achieved.
However, in some instances, What Car? found its real-world fuel economy results actually bettered the figures quoted by manufacturers using the WLTP guidelines.
The Mazda MX-5 2.0 184, Nissan Qashqai Tekna 1.3 140 and Skoda Karoq 1.5 TSI 150 were all more economical under real-world tests conditions than under the official figures – with the Mazda MX-5 bettering its 40.9mpg figure by 10.3%. Other models, including the Audi Q3 35 TFSI and VW Polo TSI 95 matched their WLTP figures, but some such as the Volvo V60 D4 and Ford Fiesta EcoBoost 140, were still more than 20% down on their WLTP figures.
What Car? tested a separate 15-car True MPG sample against results gathered on the older and less accurate New European Driving Cycle (NEDC) tests, but found none exceeded official figures under real-world conditions.
The Worldwide Harmonised Test Vehicle Procedure (WLTP) was introduced by the European Union in September 2017 to assess new vehicle emissions and fuel economy more accurately. The WLTP protocol replaced the NEDC type approval process that dated back to the 1970s and which was criticised for resulting in unrealistic economy claims.
The WLTP test features a longer assessment of each car, higher vehicle speeds and a dynamic test cycle that’s more reflective of real-world driving. Since September 2018, the tougher WLTP test has been applied to all new cars on sale.