Added 2/21/15:
Amateur sketch but it shows the direction for Z5 Coupe or Z6.
More info added 9/11/14:
The Z4 becomes the Z5 and will share with a Toyota as will a Z3 Both are RWD.
The engineering schematics for the Carbon intensive architecture is impressive. You are going to see so much for so little with the combined force of BMW and Toyota using all their resources available.
BMW wants to re-invent its Z series sports cars and make them as cutting edge and influential as the BMWi models by visual appearance and state of the art engineering to highlight a new BMW philosophy for sports cars.
Vision ConnectedDrive and 328 Homage concepts are the template for the visuals. Plans also include a slightly massaged three cylinder entirely unique and exclusive in the Z3 Mille Miglia mimicking the classic 328 to provide excellent dynamics using lightweight materials.
But since Toyota are using the joint architecture for a next gen GT86 based Sedan, its one idea under discussion in Munich, essentially a four dr Z model and potentially an SAV Z model. Nothing has come to light yet but it is a niche that BMW are investigating.
Original post:
The new Z models take their BMW design from a progression of the Vision ConnectedDrive Concept Car like the car below with a more angular and technical language recently seen on the BMW Vision Future Luxury.
All BMWs will retain the essential BMW roadster cues such as being so close to the road and the seats almost on the rear axle. A long bonnet and short rear overhang and raked rear wards front screen and a driver focused cockpit.
What I know is there is a general architecture that is modular and is different sized in each application is scaleable to cover small , medium and large applications.
The smaller one accommodates the Z3 or the GT86 replacement (or maybe a new Celica or MR2?)
The medium one will apply to the Z5 and Supra replacement .
The Z1 will be based on the BMW developed UKL architecture.
The outstanding thing is that the companies are pooling all resources so you are talking about Supercar tech such as Carbon Fibre being used in very expansive ways blended in with high strength steel , magnesium ,thermoplastic and aluminium. What I have learned it is a very beneficial feat for both companies and is currently the envy of the industry.
Some people have their nose out of joint over this arrangement.
The larger application becomes much interesting as the structural pillars and roof structure will also be CFRP. This is the larger plan destined to accommodate the next 6er and a new Lexus Coupe above the recently unveiled RZ.
The Z3 will be the sportiest Z yet combining lightweight engineering and dynamic performance from its rear wheel drive drivetrain. There is a soft top to keep weight down.
The Z3 is also under discussion to use an adaptation of BMWs new three cylinder engine as well as four and six cylinders.
The Z5 comes first. But the image attached is a look at what the Z3 could be.