Japanese automakers enjoyed solid sales and profits in fiscal 2014 thanks to the benefits of the weakened yen, and fiscal 2015 looks set to drive further growth.

However, analysts say it is critical that companies invest in sharpening their edge by adopting systems that allow them to produce vehicles more efficiently during harder times ahead — when they might have less cash on hand.

"In terms of profit, I think (fiscal 2014) was a pretty good year overall," said Satoshi Nagashima, co-managing partner at Germany-based consultancy Roland Berger, an auto industry analyst.