BMW and Ford could each be eyeing a return to formula one, according to reports.
The BMW rumour has been triggered by comments made by former F1 team owner and boss Gian Carlo Minardi, who said the revolutionary new turbo V6 rules were devised not just by current F1 suppliers Mercedes, Ferrari and Renault.
"Rumours in Germany suggest BMW's board of directors will meet in May to evaluate a return to the top category to be an engine supplier as early as 2015," Minardi said on his official website.
He said BMW officials were present during winter testing and the early races of the new V6 rules.
The return of BMW, having withdrawn its works partnership with the Sauber team at the end of 2009, would be good news for F1's controversial new engine rules, as the Japanese marque Honda is also coming back to the sport in 2015.
However, BMW has repeatedly rejected any suggestion it is contemplating a return to F1, having successfully entered the German touring car series DTM.
"Our focus has not changed," spokesman Jorg Kottmeier told Speed Week in the wake of the latest rumours.
"Formula one is not a topic for us as we are very happy in production car racing."
Elsewhere, Racecar Engineering reports that Gene Haas' new team for 2015 could be powered by Ford-branded Cosworth engines.