Car makers are racing to ensure their ranges are compliant with the new Worldwide Harmonised Light Vehicle Test Procedure (WLTP) for emissions and fuel consumption before it comes into force on 1 September.

The WLTP test will replace the New European Driving Cycle (NEDC) procedure and includes real-world testing and a greater focus on individual models and lines.

Cars sold after 1 September must have passed the new test and that has led to certain models, particularly those with heavily tuned, downsized engines and more strained high-performance units, being withdrawn from sale while they are reconfigured to meet the new WLTP test.

Doing so has been hugely costly for manufacturers. Volkswagen estimates the profit burden of meeting the new rules will be more than €1 billion (Rs 7,644 crore). Mercedes-Benz has also warned that it expects its profits to fall later this year as a result.

To gauge the impact of WLTP, an Autocar survey of car firms revealed that, while most were expecting no issues or delays due to WLTP, several have been forced to suspend production or axe models to meet the new rules.

Volkswagen Group brands have been particularly affected by the change in tests. Audi, Seat, Skoda and VW all issued a similar statement that they are restricted from disclosing exactly which model lines are due to change or are experiencing delays.

Several key VW models have had their emissions or fuel consumption ratings changed by the WLTP tests. The emissions and fuel consumption of the VW Up GTI were increased to 127-129g/km and 42mpg from 110g/km and 49mpg. The Golf R’s power output has been reduced from 306bhp to 296bhp due to WLTP, a decline understood to be due to a more restrictive exhaust system to cut NOx emissions. The Seat Leon Cupra R will also have its output reduced by 10bhp.

Several models have been suspended from sale or withdrawn because of the new test. Porsche suspended orders for its entire range due to the WLTP switch and has yet to confirm the engine range for its recently revised Macan.

The most notable car removed from sale is the VW Golf GTI, which won’t be replaced, with the next-gen model due next year. The Audi SQ5 is suspended and the 1.4-litre TFSI-engined Audi A4 has been replaced with a 2.0-litre TFSI unit with the same power output.

Skoda’s range-topping Superb has had its output cut from 276bhp to 268bhp, and the 1.4-litre TFSI Kodiaq engine has been swapped for a 1.5-litre version.

The delays in switching production to WLTP-compliant cars has caused deliveries to fall behind: Seat sources estimate a four-to-eight-month wait for bestselling models.

Elsewhere, Peugeot halted production of the 308 GTi 270 in May and build of a WLTP- compliant version will not resume until October. Similar production suspensions have affected 128bhp and 163bhp versions of the 2008, 3008 and 5008.

Who will be affected by WLTP?

Autocar UK asked car manufacturers whether their ranges were ready for the new tests.

READY:

Alfa Romeo, BMW, Citroën, Dacia, Fiat, Ford, Honda, Hyundai, Infiniti, Jaguar, Jeep, Kia, Land Rover, Lexus, Mazda, Mini, Mitsubishi, Nissan, Renault, Ssangyong, Suzuki, Toyota, Vauxhall, Volvo

CHANGES REQUIRED OR PRODUCTION AFFECTED:

Audi, Peugeot, Porsche, Seat, Skoda, Volkswagen

DECLINED TO COMMENT:

Mercedes-Benz, Smart