Porsche’s decision to end production of the remaining diesel-powered models in its range was well-timed.

At the end of this week Germany’s top court will decide whether it is legal for pre-Euro 6 diesel vehicles to be banned by city councils. Both Stuttgart (Porsche’s home city) and Leipzig want to stop older diesel vehicles entering the city limits. If the court gives the policy the green light, the repercussions could be huge.

Last summer, Porsche bosses said that they would consider killing diesel altogether at the end of next year. Bringing the decision forward is not just because of the impact of the court case, it’s also likely to be a consequence of the new round of economy and pollution testing regimes (known as RDE and WLTP) which arrive this autumn.

Older-generation diesel engines could struggle to meet the new tests. Much better to shelve diesel until a new-generation of super-clean diesels arrive within the VW Group and Porsche can consider afresh re-launching diesel models.

But Porsche’s diesel decision might also have been influenced by the fact the Tesla Model S outsold the Mercedes S-Class in Western Europe last year. Certainly, that was helped by big Tesla sales in Norway, but it’s been some time since analysts declared that ‘premium’ values were now indivisible from ‘greenness’. In plain English, the sort of customers who buy the most expensive premium cars expect a vehicle to be genuinely environmentally friendly.

As Porsche has hinted, you can’t rule out a future diesel Porsche. After all, the next-gen big diesel engines could have mild-hybrid assistance to help further reduce pollution.

But engineering sources have also told Autocar, that future diesels are also likely to have their rampant performance reigned in because hard acceleration is a direct cause of high NOx emissions. And who could imagine a gently-accelerating diesel Porsche?

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