Audi could hybridise its 2.5-litre five-cylinder engine as a way of keeping it on sale in Europe in the face of stricter emissions regulations, Audi Sport boss Rolf Michl has told Autocar.

In its current configuration, the 394bhp 'EA855' falls foul of the new Euro 7 emissions regulations coming into force in November.

Bringing it into compliance would demand a substantial engineering investment – a difficult business case to justify when the engine is deployed in just two models globally: the Audi RS3 and Cupra Formentor VZ5. 

The recent launch of the RS3 Competition Limited was seen as a potential swansong for the unit, after Audi CEO Gernot Döllner told Autocar that the EA855’s future was "still under discussion" at board level, adding that “I don’t know if we’re able to refinance the investment in EU7 regulations”.

In order to keep it on sale, sources have told Autocar that the engine would need substantial hardware changes, such as a new particulate filter, more sensitive NOx sensors, recalibrated injection mapping and higher cell-density catalysts. 

However, when pressed on whether hybridisation could instead be the answer, Michl told Autocar: “We are open to every possibility. The thoughts [on how to do that] will continue at our end. I can tell you we are still thinking in different technological possibilities.”

He added: “At the end of the day, the most important thing is the maximum amount of emotional driving experience for the compact segment.

“We are absolutely aware of the DNA of a five-cylinder engine and we are open to every possibility.”

If the 2.5-litre unit isn't updated, it won't be killed off completely, as Audi intends to keep selling it in markets with less stringent environmental mandates, such as the US. 

If it is re-engineered, Autocar previously reported that Volkswagen was looking to take it for a special Golf to mark 25 years of Volkswagen R next year.