According to the German magazine, the Z29 was conceived in 1999 to serve as a basis for the Z5 model, which would compete against the Porsche 911 and the Honda NSX.

Possibly high development costs made BMW prefer to abandon this project, and the Z4 was based on a more conventional steel unibody structure.

Thanks to the 1,160 kg total weight and the M3-derived unit delivering 343-hp, the Z29 can accelerate from 0 to 100 km/h in just 4.4 seconds, and its top speed is 270 km/h.

(Source: Auto Motor und Sport via autoblog.com, CarScoop)