The Toyota tie-up, no surprise, is to take advantage of the cost benefits that come with sharing investment and combining resources.
"It's definitely economies of scale [the reason for this collaboration]," Werner said.
"Product development of each and every car costs you a couple of billion dollars, and the roadster segment is unfortunately declining over the last couple of years — not only for us [BMW], but each and every manufacturer.
"So we decided to join forces with Toyota, as far as the development process is concerned. As far as the design is concerned, it will be absolutely unique. Not only in terms of design, but how they drive and how they handle."
MORE: 2019 BMW Z4 first-drive review
BMW recently revealed the BMW Concept Z4 at the Pebble Beach Concours D'Elegance, and again at the Frankfurt motor show in September, and it shows a very different styling direction to Toyota's FT-1 coupe concept.
The BMW product is expected to remain premium, taking advantage of the company's iDrive infotainment system and the high-end finishes expected from a product in this segment and price bracket.
When asked whether the end result would be as close a relationship as that between the Toyota 86 and Subaru BRZ, Werner promised the connection between the two vehicles would be far harder to identify.
"It will be absolutely a unique BMW product, as you would expect," Werner said.