Daimler, Renault and Nissan are to take a 3.1% stake in each other's business as part of a global tie-up of their brands.
Renault and Nissan have been in an alliance since 1999, but the new deal with Daimler will see all three sharing vehicle technology and development costs, whilst remaining seperate.
Nissan said they will co-operate to make electric cars and light commercial vehicles.
The BBC reports the companies will remain separate, but will share technology and development costs.
They will co-operate on the development of the Smart car brand - made by Daimler - and a new Renault Twingo, including electric versions, the companies said.
Engines currently made by Renault-Nissan will also be modified to fit a new range of compact Mercedes Benz cars.
Based on 2009 sales figures, Renault-Nissan is the fourth-biggest car maker in the world, with annual sales of 6.1 million vehicles.