Toyota and BMW‘s ongoing partnership was first formed in 2012 but has yet to spawn a production model. Now we know one reason why it has taken so long for anything to come from this collaboration.

Speaking to Road and Track at the Geneva Motor Show, chief engineer of the upcoming Toyota Supra, Tetsuya Tada, said the two companies took the better part of two years to hash out their different philosophies.

“We have quite a lot of differences in the terms of the way we make cars. The philosophies of the companies, as well as the mentality of Japanese people and German people are quite different. In that sense, we had to overcome a lot of differences,” Tada revealed.

The collaboration between Toyota and BMW is also quite different to the partnership with Subaru that led to the creation of the 86 and BRZ. In that case, the two automakers made sure to share as many parts as possible. By comparison, the partnership with BMW will result in two different vehicles.

“When we worked with Subaru, we started out with the aim of having as many common parts as possible between the 86 and BRZ. When we initially approached BMW, we thought it would also be aiming to have as much common parts as possible. But they had quite an unexpected reaction initially, saying ‘there’s no point in having as many common parts as possible if we cannot make a car that we each want.

“So we decided to first have a firm idea of what we, individually, wanted to make, and based on that, we approached each other and compared to see where we could have common parts,” said Tada.

The two cars set to launch through the partnership will be a successor to the BMW Z4 and a all-new Toyota Supra. The duo will share the platform but target different segments of the sports car market, use different powertrains and each will have its own, distinct design.