Porsche axes diesel ... or does it?

Porsche has moved to quell rumours that it has made the momentous decision to kill off all of its diesel-powered models, effectively immediately.

The rumours, kicked off by British magazines Autocar and AutoExpress, insisted the German sports car powerhouse was ending production of its diesel models in the face of a “cultural shift” from consumers and adds fuel to the persistent whispering campaign against diesel in the broader context.

Porsche has been embracing electrification and inching away from the compression fuel for a while, with this year's third-generation Cayenne SUV launching with three petrol engines and a delayed diesel V6.

More critically, it halted production of its Macan S Diesel on February 15. It has also stopped making the Panamera 4S Diesel.

“Diesel engines traditionally play a subordinate role at Porsche. Porsche does not develop or build diesel engines itself," said Porsche in a statement.

"Currently, the demand for diesel models is falling, whereas interest in hybrid and petrol models is increasing significantly. In light of these facts as well as the ongoing consultation with the authorities in relation to another software update, Porsche has made changes to its production planning and has set the End-of-Production date for the Macan S Diesel to 15 February 2018. This decision means that all orders for the vehicle type Macan S Diesel have already been taken out of the production program.”

Yet the story is more complex than the British reports, because Porsche is unwilling to voluntarily walk away from a third of its model mix in Western Europe, or about 15 per cent globally.

The core problem lies in two areas: the new Worldwide Harmonised Light Vehicles Test Procedure (WLPT) being phased in by the European Commission to replace the NEDC test cycle, and the recidivism of its diesel engine supplier, Audi.

The Macan Diesel stop-sale, according to insiders, is that the German Transport ministry (KBA) found five potential emissions-cheating software codes in the engine’s management software.

And the KBA is a bit fed up with that sort of thing from the Volkswagen Group.

In an enormous headache, German media reported that the KBA this month threatened to withdraw its type approval certificate for the Macan Diesel due to its questionable software codes, which would have forced Porsche to buy back every single one of them it had sold in Europe.

Porsche had been negotiating for a recall instead, but the KBA had been dragging its heels in validating Porsche’s proposed software update (well, Audi, really).

And the walls closed in, so Porsche had to stop selling the car to prevent the potential buyback liability becoming any bigger and to throw the KBA a bone.

Porsche is no longer terribly amused by this sort of thing from Audi, its diesel engine supplier, and has been getting stroppier since Dieselgate broke the entire Volkswagen Group’s reputation wide open.

“It (the recalled Cayenne V6 turbo-diesel) was the last thing we took straight from Audi and bolted in,” Porsche technical director Michael Steiner said during an interview at the 2016 Paris motor show.

“Back then it was more or less plug and play. It was in the platform we used and it was already developed.

“Today we could question it,” he said.

Porsche has done more than question it, though, and sued Audi for €200 million last year for damages over the diesel engine saga, and nobody at either company is talking about how that was concluded.

The second big issue is the WLPT, which every car-maker admits is much, much harder to comply with than the NEDC. Every vehicle must be tested with every single engine and powertrain combination, plus every major trim level and even every major option.

They aren’t the only ones to just give up claiming WLPT approval on a model too deep in its model cycle to recoup the added costs, especially if there’s any reengineering work involved. BMW did the same last month with its M3 sedan, taking it off the market and waiting until its facelift.

The announcement also came on the heels of more bad news for diesel fans, with Mercedes-Benz under fire for alleged cheat codes in its diesel software.

Germany’s Bild newspaper alleged the US Department of Justice found at least three software cheater codes in the Benz diesel management systems.

They include 'Bit 13', to shut down SCR after the cars emit 16g/km of NOx, 'Bit 14' which it claims alters the SCR behavior according to time and temperature parameters and something called “Slipguard”, which detects when the cars are on a rolling road (like in a laboratory).

The worst allegation is probably 'Bit 15', which shuts down the SCR filter entirely after 26km of driving.

Mercedes-Benz denied the allegations, insisting Bild cherry-picked a very large dossier to hurt the company and its workers.

Benz also had to recall Vito vans to reflash the diesel emission control software this month, while Volkswagen has piled up nearly 1000 freshly-built Multivan T6s while they wait for software emissions clearance from Germany’s KBA.

It will also be a nervous week for Europe’s car-makers, with Germany’s Federal Administrative Court in Leipzig expecting to rule on Thursday on whether to ban pre-2015 diesel cars from German cities.

The case, brought by environmental group Umwelthilfe, is one of a raft of such cases around Germany, with others in Stuttgart, Dusseldorf and Munich as the country battles with airborne NOx levels well above the World Health Organization’s recommended limit of 40g/m3.

Munich’s average NOx value in 2017 was 78, Stuttgart was close behind at 73, Cologne hit 62 and major cities like Hamburg, Kiel, Dusseldorf, Heilbronn and Ludwigsburg were all above 50.