Audi could keep its venerable five-cylinder turbo engine alive for another generation despite forthcoming emissions regulations threatening the existence of the unique motor configuration, which has featured in the brand's portfolio for 50 years.

Audi introduced its first in-line five in 1976 for its flagship 100. It has kept a five-pot in its line-up ever since, deploying the arrangement in sporting legends including the Quattro and RS2.

Today it only uses the engine in the RS3 now the TT RS and RS Q3 have been retired, but it also supplies the 'EA855' 2.5-litre lump to sibling firm Cupra for the Formentor VZ5.

Audi recently launched the RS3 Competition Limited as a swansong for its hardcore hot hatch, and there were suggestions it could serve as the final outing for the engine that powers it. CEO Gernot Döllner said at the time that he was unsure the firm would be "able to refinance the investment in EU7 regulations", which come into effect from November.

As previously reported, the engine would need substantial modifications to its filters, emissions sensors, injection system and catalysts to remain compliant, which would be especially costly given that the engine is used by just two low-volume cars.

Now, however, Audi Sport boss Rolf Michl has suggested the five-pot could remain in Audi's future range as the firm commits to maintaining a broad line-up of performance models and seeks to double down on its strong sporting heritage.

"We're well aware about the historical meaning of the five-cylinder," he told Autocar. "Evaluations are still running, and people who know me know that I also have a personal relationship to the five-cylinder engine.

"It's so characteristic and also deeply rooted in history - so let's see."

Michl has been responsible for all three generations of the RS3 so far - all five-cylinder-powered - in his various positions within Audi's sports car division. He said the model plays an important role as the most affordable car in the RS line-up, and that could strengthen the business case for renewing both it and its engine.

"The entrance into the RS world is important because having a brand statement like that is amazing," Michl said. "Emotion starts in the compact segment."

No decision has yet been made on what a successor might look like, he added: "Negotiations are ongoing, so we're not at the decision point yet. Everybody really knows about the meaning, and therefore we're still evaluating with our colleagues from Audi AG."

Hybridisation could be one means of reducing the five-cylinder's emissions output and keeping it compliant, as Audi has done with the RS5's V6, but doing so also comes with significant cost and weight implications.

Whichever path it chooses, Audi is likely to chase higher volumes from any future five-cylinder-powered cars in a bid to recoup the necessary investment on the engine. The firm does not break out individual sales figures in its annual reports, but Audi Sport shifted 36,000 cars globally last year, and the RS3 will have accounted for only a small percentage of that.

Making the powerplant more widely available across the Volkswagen Group portfolio would help to generate a higher return on investment.

The RS3 and Formentor are the only cars to employ the engine currently, but they each use the MQB platform that underpins every mid-sized Volkswagen Group model. Autocar has previously reported that an extreme special edition of the Golf R could use the motor next year, potentially creating the most powerful iteration yet of the hatchback.