Sergio Marchionne has said that a third partner for Fiat and Chrysler could be considered to further increase efficiencies and cut development costs.

In an interview at the Detroit Show reported by Bloomberg, he returned once again to his oft-stated theme that the auto industry's long-term winners will be the companies able to exploit large scale economies and spread costs over big volumes. “There may be a third partner,” Marchionne said. “You need to build a new level of efficiency.”

To create the necessary car-making efficiencies, automotive groups need to build from 8-10m vehicles a year, Marchionne said.

Bloomberg noted that Marchionne’s renewed interest in expanding the Fiat-Chrysler alliance comes as he considers lowering his 2014 sales target to 5.7m cars from a previous forecast of 5.9m. Fiat may globally lose 500,000 vehicle sales annually as a result of the European debt crisis, he said.

“This is a volume business,” Marchionne said in an interview with Bloomberg Radio. “We need to see whether other opportunities are available.”

In other media interviews conducted around the NAIAS, Marchionne reportedly said that he would need at least until after 2015 to fully merge Fiat and Chrysler and leave his post.

When asked how long he would stay in his job, Marchionne told the Detroit Free Press: “Nothing is going to happen until after 2015 - unless I get hit by a bus.”

Fiat now controls 58.5% of Chrysler Group