Together, Honda and Nissan would also pose more of a threat to Toyota Motor Corp., which is the world’s biggest automaker followed by Volkswagen AG.

Speculation grows over a potential Honda-Nissan merger that could challenge Chinese automakers and impact global vehicle sales.

Honda and Nissan plan to merge as the two Japanese firms seek to fight back against competition from the Chinese car industry. The integration would create one of the world's biggest car producers alongside Toyota,