Apple worked with Chinese automaker BYD for years, developing batteries that helped lay the groundwork for tech used today, according to people familiar with the situation.

For years, Apple was rumored to be working on a futuristic self-driving car, with the company tied to collaborations with Volkswagen and even a potential deal to buy McLaren at one point. That never happened and the project was canned after 10 years,

Apple secretly collaborated with Chinese automaker BYD to develop long-range electric vehicle battery technology as part of its now-nixed Apple

Before the Project Titan was scrapped, Apple reportedly worked with Chinese automaker BYD on custom batteries for Apple Car for years, but ultimately abandoned that partnership too.

As reported by Bloomberg on Wednesday, Apple has worked closely with Chinese automaker BYD. Both companies reportedly reached an agreement around 2017 to build batteries using lithium iron phosphate cells (LFP).