Rumours suggesting Porsche is set to reveal its own four-cylinder boxer engine at the Frankfurt motor show in September have been emphatically denied by officials from the German car maker, who suggest such a move is at least three years away.

"It is no real secret that we are working on a four-cylinder engine. But it is still in an early development phase. On current planning, it will be another three years at least before we will be ready to reveal anything official on this subject," a Zuffenhausen-based Porsche official with knowledge of future product activities revealed to Autocar, adding, "It is not due before 2016." 

The new turbocharged four-cylinder direct-injection boxer engine is set to share its architecture with the larger six-cylinder unit already in use in the Boxster, Cayman and 911.

Its first appearance is expected to be in a facelifted version of the third-generation Boxster and recently launched second-generation Cayman – both due to head into showrooms in 2016.

However, in-line four-cylinder engines will appear in Porsche models before 2016. Volkswagen-sourced turbocharged 2.0-litre petrol and common rail diesel units will feature in the upcoming Porsche Macan SUV