General Motors and Honda are teaming up in a budding alliance between two auto giants that were at one time bitter rivals.

GM and Honda announced a nonbinding memorandum of understanding.

The agreement follows preliminary talks between the Detroit auto maker and the Japanese car giant aimed at “establishing a North American automotive alliance,” the companies said in a press release.

Fierce competitors back in the 1970s and ‘80s as American car companies found their hold on the U.S. market challenged by Japanese imports, the two companies are now exploring plans to “share common vehicle platforms,” as well as gas and electric engines that fit the platforms.

Despite their historic rivalry, in more recent years the two competitors have buried the hatchet, with cooperation on various projects going back two decades now.

GM and Honda said they plan to immediately launch “co-development planning discussions,” with plans to begin engineering work early next year.

The moves are expected to help both companies cut costs, with the two automakers planning to share engineering and research and development costs.

“This alliance will help both companies accelerate investment in future mobility innovation by freeing up additional resources. Given our strong track record of collaboration, the companies would realize significant synergies in the development of today’s vehicle portfolio,” General Motors President Mark Reuss said in the press release.

The agreement follows on the heels of a deal inked in April between GM and Honda to develop a pair of new electric vehicles for Honda. The new electric cars will be based on an EV platform designed by GM, using Ultium batteries.

“Through this new alliance with GM, we can achieve substantial cost efficiencies in North America that will enable us to invest in future mobility technology, while maintaining our own distinct and competitive product offerings,” said Seiji Kuraishi, executive vice president of Honda Motor Co., Ltd.