Both Lotus and Red Bull could reportedly leave Formula 1 at the end of the season after doubts emerged regarding possible takeovers.
Christian Horner had hinted that Volkswagen were interested in buying out the four-time constructors' champions, but the German company has been hit by allegations that a number of their production cars have been producing higher emissions than legally allowed.
The Red Bull boss has since told NBC Sports that the deal "seemed to go up in smoke" as a result of the scandal.
Such is the situation with the Milton Keynes-based constructor that they are said to be considering leaving grand prix racing at the end of the season, if they fail to receive a competitive engine for 2016.
Meanwhile, Renault have come under pressure to conclude their proposed takeover of Lotus before the deadline, which is believed to be in the coming days.
F1 boss Bernie Ecclestone has suggested that he is unsure why Renault have failed to finalise their deal so far.
However, according to Autoweek, the stumbling block could be that the French manufacturer is seeking a higher payment from F1 organisers for setting up a works team, but it is thought that Ecclestone is reluctant to offer further funds to Renault.
Chris O'Keefe
