Auto makers Renault of France and Nissan of Japan said on Friday that they planned to tighten their 10-year-old alliance and expected gains worth 1.5 billion euros (2.1 billion dollars) this year.
Renault-Nissan said it had formed a team to "accelerate and strengthen" the ties that have linked the two companies since 1999.
"Today, we must go further," said alliance chairman Carlos Ghosn.
"The search for synergies is no longer optional -- it is an obligation."
The companies said in a statement that their bolstered cooperation at a time when the auto sector is under pressure from a global economic downturn could mean financial gains worth 1.5 billion euros in 2009, shared equally.
Renault and Nissan have so far joined forces to share technology, standardise production methods and to develop their worldwide presence.
Renault has a 44 per cent stake in Nissan.