Collaboration with Toyota came because "Z4 roadster segment is declining."
BMW has finally confirmed that its jointly-developed sports car, produced in collaboration with Toyota, will first spawn a Z4 roadster, arriving as a fresh model in 2017. The company's corporate and governmental affairs spokesman, Kai Lichte, told Motoring that the 2017 Z4 will arrive with an inline-six engine, rejecting rumors of an initial hybrid model. According to Lichte, the joint-development with Toyota was brought about because the "Z4 roadster segment is declining."
The spokesman did not offer any additional details regarding the next Z4, but it's assumed that it will employ a new 3.0-liter engine making approximately 335 horsepower.