Renault SA and Nissan Motor Co. Ltd. say they will increase the amount of parts they purchase together to $21 billion annually from $15 billion, say reports.

The two auto makers have a joint purchasing agreement for the procurement of common parts to be used in each other’s vehicles. Renault and Nissan say most of the increase will be in parts primarily for use in powertrains.

Nissan holds a 15% stake in Renault, which in turn has a 44.4% stake in Nissan.